The present invention relates to an economical graphitic carbon nitride (g-C3N4) as a photoelectrode (photoanode) material. More specifically, the present invention relates to a bimetallic system of iron and cobalt with bulk graphitic carbon nitride (Fe-Co/g-C3N4). The photoelectrode can be used for solar-water splitting in terms of generating the highest current density at the thermodynamic potential required to oxidize water (1.23 V vs Reference Hydrogen electrode (RHE)). The photoelectrode is prepared by using the low-cost yet efficient film deposition technique.
BACKGROUND OF THE INVENTION
In present time, the problems of energy crisis and environmental pollution are increasing day by day, and the development of renewable energy and clean energy is on priority. The electrochemical decomposition water has attracted extensive attention because of its environmentally friendly procedure, high product purity and no greenhouse gas emission.
Graphitic carbon nitride (g-C3N4) is one of the low cost, efficient and non-toxic photoelectrode materials for photoelectrochemical water splitting. Graphitic carbon nitride is an n-type semiconductor material, with a reported band gap of 2.7 eV, which lies in the visible range, in its pristine form and acts as a photoanode. However, it has posed the problem of low photocurrent density in its pristine form. Good results have been obtained through use of noble metals, but their use is limited by the cost factor. To overcome of these problems, the inventors of present invention have developed a bimetallic system of iron and cobalt in the weight ratio of 1:1, 1:3, 1:5, 1:7 and 1:9 with bulk graphitic carbon nitride (Fe-Co/g-C3N4) using melamine, iron chloride hexahydrate and cobalt chloride hexahydrate as the precursor materials. The present technology has produced a photocatalyst product which results in a version of g-C3N4, both in terms of photoelectrochemical performance and the economic point of view. The inventor have fabricated the uniform and defect free thin films of Fe:Co co-doped g-C3N4 via a novel, economic and efficient film deposition technique utilizing the combined effect of centrifugation and screen-printing technologies. The novel product generated the current density in the range of 4.9 mA/cm2to 6.21 mA/cm2 which is the highest achieved current density for g-C3N4 under illumination. This current density resulted in the generation of around 92 umol of H2/I1 to 114 umol of H2/I1 and was stable

under illumination for more than 11 h to 20 h without any protective layer which is much higher than the reported g-C3N4 photoanode in prior art literature.
PRIOR ART
Graphite carbon nitride (g-C3N4) is well known as one of the most promising materials for photocatalytic activities, such as CO2 reduction and water splitting, and environmental remediation through the removal of organic pollutants. On the other hand, carbon nitride also pose outstanding properties and extensive application forecasts in the aspect of field emission properties.
Liu, D. et. al. in Modulation of the excited-electron recombination process by introduce g-C3N4 on Bi-based bimetallic oxides photocatalyst discloses Bi-based bimetallic oxides photocatalyst. Bi7.53Coo.47On.92 was synthesized and the graphite phase carbon nitride (g-C3N4) was loaded, and a novel composite photocatalyst Bi7.53Coo.47On.92/g-C3N4 was obtained as well. The photocatalyst Bi7.53Coo.47O11.92, possessed tetragonal crystal structure, with the introduction of g-C3N4, the H2 production reached the maximum about 108 umol under continuous visible light irradiation for 4h, which was 13 times higher than that of pure g-C3N4 photocatalyst. A series of studies shown that the g-C3N4 on the surface of Bi7.53Coo.47O11.92 provided the more active sites and improved the efficiency of photo-generated charge separation by means of several characterizations such as SEM, XRD, XPS, element mapping, UV-vis DRS and FTIR. etc.
Although in the present invention different bimetallic component are used. The H2 production reached the higher value than the disclosed in prior art.
Wang, R., et. al. inln-situ synthesis o/Fe and O co-doped g-Cs/N4 to enhanceperoxymonosulfate activation with favorable charge transfer for efficient contaminant decomposition. J. Taiwan Inst. Chem. Eng. 115, 198-207. https://doi.org/10.1016/jjtice.2020.10.022 discloses material as a Fe:0 doped g-C3N4. The material is used as a photocatalyst for the degradation of dye 01. However, the preparation includes a high temperature and hence, a high energy consumption pyrolysis at 500°C. On the contrary, the present material, which is a bimetallic system of Fe and Co g-C3N4 was synthesized at much lower temperature of 70°C. The present material was then deposited in the form of a thin film which can either be used as a

photocatalyst for dye degradation or as a photoanode for photoelectrochemical splitting of water or even in a solar cell. The highly efficient and a low-cost material was developed by applying simple, cost effective film deposition technique utilizing much lesser energy than the work cited in this document.
CN108842168A discloses a kind of two-step electrochemical method preparation g-CsN^ MMO compound film optoelectronic pole, the invention mentions the synthesis of layered-double hydroxide (LDH) g-C3N4 via the electrochemical method where the use of noble metal, Platinum has been used. The material is expected to show good photocatalytic activity as a photoelectrode material in the solar cells. A very high energy consumption of 150 V and at 600°C was made in the synthesis procedure. On the other hand, the present material is a Fe:Co (1:1) based bimetallic g-C3N4 used as a photoelectrode in the aqueous system (solar water splitting). The material was synthesized at only 70°C which is much less than 150 V and 600 °C of energy consumption. The film deposition was done in a controlled manner by simply utilizing the screen-printer sheet covered FTO substrate in a centrifuge system at room temperature, with no use of any rare-earth metals or noble metals.
OBJECTIVES OF THE INVENTION
In order to solve the technical problems in the prior art, the invention provides a carbon-based bimetallic composite material with g-C3N4 to achieve the highest photocurrent density for an increased efficiency. This can be applied in the solar water splitting and in the solar cells.
The main objective of this invention is to develop a best possible version of g-C3N4 to achieve the highest photocurrent density for an increased efficiency towards the applications in the solar water splitting and in the solar cells.
Another objective of the invention is to utilize two of the most efficient transition metals for water oxidation viz. Fe and Co in a bimetallic system, in order to enhance the reaction kinetics of g-C3N4.
Another objective of the invention is to fabricate the photoanode based on bimetallic system of Fe:Co co-doped g-C3N4 via a simple, economic and efficient film deposition technique.

Another objective of the invention is to avoid using gold contact for the conductivity enhancement. The novel bimetallic system based on transition metals doped g-C3N4 deposited via simple and economic deposition technique resulted in the increased current density and hence, efficiency without the aid of gold or any other rare earth metals.
SUMMARY OF THE INVENTION
Graphitic carbon nitride (g-C3N4) is an n-type semiconductor used as a photo-anode in photo-electrochemical splitting of water for H2 generation. However, performance of pristine g-C3N4 is poor in terms of photocurrent density obtained. A bimetallic system of transition metals known for high water oxidation kinetics, iron and cobalt with graphitic carbon nitride (Fe-Co/ g-C3N4) in the wt. ratio of 1:1 was synthesized by the pyrolysis of melamine, iron (III) chloride hexahydrate and cobalt (II) chloridehexahydrate. Fe-Co/ g-C3N4 photoelectrodes were fabricated using a simple and low-cost deposition technique, where the controlled particle size and a uniform and defect-free coating of film were ensured by the centrifugation technique in combination with the screen-printer. As a result, the developed photoelectrode was nanocrystalline where the crystal grains were of nanometer range of sizes. The current density of as high as 6.1 mA/cm2 was generated which is the highest current density for g-C3N4 without the use of any rare-earth metals. Moreover, the stability of the photoanode was measured for 20 hours in the photoelectrochemical medium without the application of any protective overlayer coating.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 shows the schematic diagram for the cleaning procedure of FTO (Fluorine doped
tin oxide) substrates
Figure 2 shows the schematic diagram for the synthesis of bimetallic system of iron and
cobalt doped g-C3N4.
Figure 3 shows the diagram of fabricated electrode of prepared Fe-Co/g-C3N4.
Figure 4 shows the surface morphology of Fe-Co/g-C3N4 by using scanning electron
microscopy.
Figure 5 shows the phase determination of Fe-Co/g-C3N4 by using XRD peak analysis.
Figure 6 shows the elemental composition of Fe-Co/g-C3N4 by using EDX spectroscopy.

Figure 7 shows the absorption spectrum of UV-VIS of thin film of 2 mg of Fe-Co/g-C3N4
in 10 ml of isopropanol on FTO.
Figure 8 shows the absorption spectrum of UV-VIS of thin film of 4 mg of Fe-Co/g-C3N4
in 10 ml of isopropanol on FTO.
Figure 9 shows the absorption spectrum of UV-VIS of thin film of 6 mg of Fe-Co/g-C3N4
in 10 ml of isopropanol on FTO.
Figure 10 shows the absorption spectrum of UV-VIS of thin film of 8 mg of Fe-Co/g-C3N4
in 10 ml of isopropanol on FTO.
Figure 11 shows the absorption spectrum of UV-VIS of thin film of 10 mg of Fe-Co/g-C3N4
in 10 ml of isopropanol on FTO.
Figure 12 shows the n-type conductivity of thin film of 2 mg of Fe-Co/g-C3N4 in 10 ml of
isopropanol on FTO by Mott-Schottky analysis.
Figure 13 shows the n-type conductivity of thin film of 4 mg of Fe-Co/g-C3N4 in 10 ml of
isopropanol on FTO by Mott-Schottky analysis.
Figure 14 shows the n-type conductivity of thin film of 6 mg of Fe-Co/g-C3N4 in 10 ml of
isopropanol on FTO by Mott-Schottky analysis.
Figure 15 shows the n-type conductivity of thin film of 8 mg of Fe-Co/g-C3N4 in 10 ml of
isopropanol on FTO by Mott-Schottky analysis.
Figure 16 shows the n-type conductivity of thin film of 10 mg of Fe-Co/g-C3N4 in 10 ml of
isopropanol on FTO by Mott-Schottky analysis.
Figure 17 shows the j-V curve of thin film of 2 mg of Fe-Co/g-C3N4 in 10 ml of isopropanol
on FTO for the photocurrent density determination.
Figure 18 shows the j-V curve of thin film of 4 mg of Fe-Co/g-C3N4in 10 ml of isopropanol
on FTO for the photocurrent density determination.
Figure 19 shows the j-V curve of thin film of 6 mg of Fe-Co/g-C3N4 in 10 ml of isopropanol
on FTO for the photocurrent density determination.
Figure 20 shows the j-V curve of thin film of 8 mg of Fe-Co/g-C3N4 in 10 ml of isopropanol
on FTO for the photocurrent density determination.
Figure 21 shows the j-V curve of thin film of 10 mg of Fe-Co/g-C3N4 in 10 ml of isopropanol
on FTO for the photocurrent density determination.
Figure 22 shows the charge transfer resistance of thin film of 2 mg of Fe-Co/g-C3N4 in 10
ml of isopropanol on FTO by Nyquist plots.

Figure 23 shows the charge transfer resistance of thin film of 4 mg of Fe-Co/g-C3N4 in 10
ml of isopropanol on FTO by Nyquist plots.
Figure 24 shows the charge transfer resistance of thin film of 6 mg of Fe-Co/g-C3N4 in 10
ml of isopropanol on FTO by Nyquist plots.
Figure 25 shows the charge transfer resistance of thin film of 8 mg of Fe-Co/g-C3N4 in 10
ml of isopropanol on FTO by Nyquist plots.
Figure 26 shows the charge transfer resistance of thin film of 10 mg of Fe-Co/g-C3N4 in 10
ml of isopropanol on FTO by Nyquist plots.
Figure 27 shows the comparison of absorption spectrum of UV-VIS spectroscopy of Fe-
Co/g-C3N4 with varying slurry weight ratios
Figure 28 shows the comparison of current densities of Fe-Co/g-C3N4 with varying slurry
weight ratios
Figure 29 shows the comparison of charge transfer resistance of Fe-Co/g-C3N4 with varying
slurry weight ratios
Figure 30 shows thej-V curves of Fe-Co/g-C3N4 (6 mg in 10 ml isopropanol) annealed at
200°C
Figure 31 shows thej-V curves of Fe-Co/g-C3N4 (6 mg in 10 ml isopropanol) annealed at
400°C
Figure 32 shows thej-V curves of Fe-Co/g-C3N4 (6 mg in 10 ml isopropanol) annealed at
600°C
Figure 33 shows the experimental setup for the electro/photoelectrochemical
characterization of Fe-Co/g-C3N4
Figure 34 shows the photostability curve of Fe-Co/g-C3N4 (6 mg in 10 ml isopropanol)
annealed at 400°C
Figure 35 shows the j-V curves of g-C3N4 doped with 1:1 wt% of other bimetallic system
of transition metals viz. Ni-Zn, Fe-Cu and Ni-Fe (6 mg in 10 ml isopropanol) annealed at
400°C.
DETAILED DESCRIPTION OF INVENTION
While the disclosure is susceptible to various modifications and alternative forms, specific aspects thereof have been shown by way of examples and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular

forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention.
The Applicants would like to mention that the studies carried out (below) are to show only those specific details that are pertinent to understanding the aspects of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
One embodiment of the present invention relates to a photoelectrode comprising bimetallic system of iron and cobalt with graphitic carbon nitride (Fe-Co/g-C3N4) uniformly coated on a fluorine tin oxide (FTO) glass.
In one of the embodiments, the photoelectrode wherein iron and cobalt are having weight ratio of 1:1 to 1:9.
One embodiment of the present invention relates to the photoelectrode wherein iron and cobalt are having weight ratio of 1:3, 1:5, 1:7.
Yet another embodiment of the present invention relates to the photoelectrode which is
photoanode.
One embodiment of the present invention relates to the photoelectrode having stability of
more than 20 hours.
In one of the embodiments, the photoelectrode which is devoid of rare earth metal.
One embodiment of the present invention relates to a method of preparing photoelectrode, comprises of following step:
i. dissolving equimolar amount of melamine, cyanuric acid and barbituric acid
in water and stirring for 6 hours; ii. filtering the mixture of step (i) and drying the residue for 12 to 14 hours at
70 °C; iii. grinding and dissolving the residue in isopropyl alcohol having concentration of 3mg/ml;

iv. dissolving 5 mol % of iron (III) chloride hexahydrate (FeCh.6ihO) and 5
mol % of cobalt (II) chloride hexahydrate (C0CI2.6H2O) into the solution
obtained in step (iii) and stirring for 12 hours; v. filtering the mixture of step (iv) and drying the residue for 12 to 14 hours at
70 °C; vi. Grinding and heating the residue at temperature 550 °C for 4 hours; vii. dissolving the residue of step (vi) in isopropyl alcohol having concentration
of 3mg/ml to obtain suspension; viii. Centrifugating the suspension at 3000 rpm for 10 minutes and obtaining
supernatant liquid; ix. depositing the supernatant liquid of step (viii) on cleaned FTO glass on
specific exposed area by screen printer sheet and centrifugation method; x. annealing the coated FTO glass in Argon atmosphere at 200°C, 400°C and
600°C; xi. attaching the copper wire with silver conductive ink into the blank area of
the FTO glass substrate to obtain photoelectrode.
In one of the embodiments, the photoanode as and when applied for photoelectrochemical splitting of water for hydrogen generation or for solar cells.
METHODOLOGY
The methodology adhered to in experiments was synthesis and fabrication of the
photoelectrode material and photoelectrodes respectively, followed by physical and
photoelectrochemical (PEC) characterization of the photoelectrodes. Based on the
photoelectrochemical (PEC) performance of the photoelectrodes, optimization was done in
the synthesis step and the subsequent experiments were performed using the same
methodology.
Physical characterization:
• XRD characterisation
• EDX spectroscopy
• UV-visible spectroscopy
Photoelectrochemical characterization:
• Mott-Schottky analysis

• Linear Sweep Voltammetry (LSV)
• Electrochemical Impedance Spectroscopy (EIS)
Synthesis of photoelectrode material
Preparation of graphitic carbon nitride from melamine, cyanuric acid and barbituric acid (g-C3N4 (MCB))
Melamine (C3H6N6), cyanuric acid (C3H3N3O3) and barbituric acid (C4H4N2O3) were used to create a supramolecular complex of carbon nitride. Equimolar amounts of melamine, cyanuric acid and barbituric acid were taken in proportionate amounts of water (40 ml of water for 1 mole of cyanuric acid). The complex was mixed in an automatic magnetic stirrer for 6 hours. A resulting white complex was obtained after filtration using filter paper. The complex was placed in a hot air oven at 70°C for 12-14 h drying. Following this, a white amorphous mass of the complex was obtained, which was grinding to fine powder using a mortar and pestle. The white powder obtained finally is graphitic carbon nitride powder. It was termed as g-C3N4 for further reference.
The obtained carbon nitride powder was taken in the concentration of 3 mg/ml of isopropyl alcohol (IPA) and a suspension was prepared by sonication in a bath sonicator for 10 hours. Following this, the suspension was centrifuged at 3000 rpm for 10 minutes. The exfoliated graphitic carbon nitride particles were obtained after removing the solution with unexfoliated particles. A solution of the exfoliated graphitic carbon nitride particles in IPA was made with the concentration of 1.2 mg/ml.
Preparation of bimetallic system of iron and cobalt with graphitic carbon nitride (Fe-Co/g-C3N4)
A novel method was devised for preparation of a bimetallic system of iron and cobalt with graphitic carbon nitride (Fe-Co/g-C3N4). Melamine, iron (III) chloride hexahydrate (FeCl3.6H20) and cobalt (II) chloride hexahydrate (C0CI2.6H2O) were used to prepare the precursor. 5 mol% of both FeCb.6H20 and C0CI2.6H2O with respect to melamine were taken in a beaker. For every 1 g of melamine, 40 ml of H2O was taken. The solution was stirred overnight in a magnetic stirrer. The solution was filtered using filter paper (several washes using water) and the obtained residue was kept for drying overnight in a hot air oven at 70 °C. A light brown amorphous mass was obtained which was crushed to powder form using mortar and

pestle. The obtained precursor was heat treated in a furnace at a temperature of 550 °C for 4 hours in air at normal atmospheric conditions. The temperature was achieved by increasing the temperature at an increasing rate of 6 °C/min. A brownish residue was obtained and was subsequently crushed to powder form.
The obtained Fe-Co/g-C3N4 bimetallic system and isopropyl alcohol (IPA) was taken in the concentration of 3 mg/ml and a suspension was prepared by sonication in a bath sonicator for 10 hours. Following this, centrifugation of the suspension was done at 3000 rpm for 10 minutes. The exfoliated graphitic carbon nitride particles were obtained after removing the solution with unexfoliated particles collected at the bottom of the centrifuge tubes. The suspension finally obtained had a concentration of 1.2 mg/ml.
Fabrication of photoelectrodes
FTO glass was used as the substrate on which the thin film of the sample was deposited. The blank FTO's were cleaned by first sonication in iso propyl alcohol (IPA) for 10 minutes, followed by sonication in dilute HCl solution (2 ml HCl in 100 ml of deionized water) for -10 mins, which was then sonicated in deionized (DI) water for around 10 mins and then placed them in ethanol after sonication. The blank FTO samples placed in ethanol were placed in the bath sonicator for 5 mins just before starting the deposition process. A clean petri dish was taken and blank FTO samples with an exposed area of 0.25 cm2 (remaining surface of the surface was covered with tape) were placed in it. The FTO substrates were covered with a screen printer sheet (140 mesh size, 0.5 cm x 0.5 cm) and the prepared slurry was poured onto it in such a way that the blank FTOs were just submerged under the solution. This was done to ensure a smooth and a uniform film deposition. The submerged FTO substrate placed under the screen printer sheet was subjected to centrifugation at 1500 rpm for 5 to 30 minutes for the in-time deposition of the thin film on the substrate. Here IPA acts as the binding agent and the centrifugation under the screen-printer helped to obtain a stable thin film of graphitic carbon nitride of controlled particle size on the blank FTO glass. The coated films were then heated at 70°C to evaporate IPA, thereby leaving behind a thin film of the sample. The process was repeated to obtain samples with multiple coatings of the sample by varying the weight ratios of sample in IPA. A quartz tubular trap was used for annealing the samples in Argon atmosphere at 200°C, 400°C and 600°C in a muffle furnace.

Silver conductive ink was used to attach the copper wire to the blank area of the FTO glass substrate and the remaining blank surface was coated with non-conducting epoxy glue. Thus, finally the photoelectrodes were prepared.
Experimental setup for photoelectrochemical characterization
For photoelectrochemical measurements, we used a three-electrode photoelectrochemical cell (inner diameter = 4 cm, height = 5 cm, diameter of holes = 3 mm, 11 mm, 3mm). For the counter electrode, a Pt-wire was chosen and for the reference electrode, a 3M KC1 Saturated Ag/AgCl electrode was chosen for taking electrochemical and photoelectrochemical measurements of the photoelectrodes. The electrolyte used was 0.5 M Na2S04. A Xe-short arc lamp of 1000 W/m2 intensity was used as the light source to generate photocurrent response from the graphitic carbon nitride photoelectrode. Table 1. Comparison table for Fe-Co/g-C3N4 photoelectrodes for varying film thicknesses by changing the weight ratios in slurry

S.No. Weight ratio of sample in lOmloflPA
(mg/ml) Ret (Charge
transfer
resistance)
(kH/cm2) under light* Current density, jP (mA/cm2) in pH 6, under illumination* Efficiency (%)
1 2 10.92 3.21 1.35
2 4 9.86 3.72 2.00
3 6 8.12 3.89 3.04
4 8 5.31 6.12 2.43
5 10 7.73 4.91 2.16
Intensity of light - 100 mW/cm2, Source -Xenon Short arc lamp for visible light (Osram).

Example 1. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 2 mg /10 ml of IPA for the applications in photo water splitting and solar cells.
The precursor slurry of 2 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 200°C in N2 for six hours.
Example 2. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 4 mg /10 ml of IPA for the applications in photo water splitting and solar cells.
The precursor slurry of 4 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 200°C in N2 for six hours.
Example 3. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 6 mg /10 ml of IPA for the applications in photo water splitting and solar cells.
The precursor slurry of 6 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 200°C in N2 for six hours.
Example 4. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 8 mg /10 ml of IPA for the applications in photo water splitting and solar cells.
The precursor slurry of 8 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 200°C in N2 for six hours.
Example 5. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 10 mg /10 ml of IPA for the applications in photo water splitting and solar cells. The precursor slurry of 10 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 200°C in N2 for six hours.
Example 6. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 4 mg /10 ml of IPA for the applications in photo water splitting and solar cells.

The precursor slurry of 4 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 400°C in N2 for six hours.
Example 7. Fabrication of Fe-Co/g-C3N4 photoelectrode with concentration of 4 mg /10 ml of IPA for the applications in photo water splitting and solar cells.
The precursor slurry of 4 mg of sample /10 ml of IPA was poured onto the FTO covered with a screen printer and was centrifuged. IPA was evaporated at 70°C and the film was finally annealed at 600°C in N2 for six hours.
The Fe-Co/g-C3N4 photoelectrode fabricated using the bimetallic system of transition metals (Fe and Co) resulted in a good efficiency without the addition of any rare earth metals and high end deposition techniques, such as atomic layer deposition, sputtering, chemical vapor deposition etc. The deposition technique employing a screen printer in the centrifugation surprisingly resulted in the uniform and controlled film morphology and thickness, which ultimately increased the current density to 6.21 mA/cm2.
Table 2. Comparative analysis of photocurrent density generation of g-C3N4 upon doping with other bimetallic systems of transition metals.

Photoelectrode material Wt.% ratio of dopants
(1:1), Annealing temperature
400°C Photocurrent density at 1.23 V vs. RHE (mA/cm2)
Fe-Co/g-C3N4 6.21
Ni-Zn/g-C3N4 5.95
Fe-Cu/g-C3N4 6.18
Ni-Fe/g-C3N4 6.12

We Claim:

1. A photoelectrode comprising bimetallic system of iron and cobalt with graphitic carbon nitride (Fe-Co/g-C3N4) uniformly coated on a fluorine tin oxide (FTO) glass.
2. The photoelectrode as claimed in claim 1 wherein iron and cobalt are having weight ratio of 1:1 to 1:9.
3. The photoelectrode as claimed in claim 1 wherein iron and cobalt are having weight ratio of 1:3.
4. The photoelectrode as claimed in claim 1 wherein iron and cobalt are having weight ratio of 1:5.
5. The photoelectrode as claimed in claim 1 wherein iron and cobalt are having weight ratio of 1:7.
6. The photoelectrode as claimed in claim 1 is photoanode.
7. The photoelectrode as claimed in claim 1 having stability of more than 20 hours.
8. The photoelectrode as claimed in claim 1 which is devoid of rare earth metal.
9. A method of preparing photoelectrode as claimed in claim 1, comprises of following step:
i. dissolving equimolar amount of melamine, cyanuric acid and barbituric acid
in water and stirring for 6 hours; ii. filtering the mixture of step (i) and drying the residue for 12 to 14 hours at
70 °C; iii. grinding and dissolving the residue in isopropyl alcohol having
concentration of 3mg/ml; iv. dissolving 5 mol % of iron (III) chloride hexahydrate (FeCb.6H20) and 5 mol % of cobalt (II) chloride hexahydrate (C0CI2.6H2O) into the solution obtained in step (iii) and stirring for 12 hours; v. filtering the mixture of step (iv) and drying the residue for 12 to 14 hours at
70 °C; vi. Grinding and heating the residue at temperature 550 °C for 4 hours; vii. dissolving the residue of step (vi) in isopropyl alcohol having concentration
of 3mg/ml to obtain suspension; viii. Centrifugating the suspension at 3000 rpm for 10 minutes and obtaining supernatant liquid;

ix. depositing the supernatant liquid of step (viii) on cleaned FTO glass on specific exposed area by screen printer sheet and centrifugation method;
x. annealing the coated FTO glass in Argon atmosphere at 200°C, 400°C and 600°C;
xi. attaching the copper wire with silver conductive ink into the blank area of the FTO glass substrate to obtain photoelectrode.
10. The photoanode as claimed in claim 1 as and when applied for photoelectrochemical splitting of water for hydrogen generation or for solar cells.