NOVELTY - Preparation of a heterojunction photoelectrode of photoelectrochemical cell using semiconductor nanocomposite material involves synthesizing alpha -iron oxide nanorods, placing alpha -iron oxide nanorods sample in 200 degrees C atomic layer deposition system in a reaction chamber, adding diethyl zinc as zinc source and water as oxygen source, depositing zinc oxide on alpha -iron oxide nanorods sample, placing the sample in a muffle furnace, sintering and annealing, cooling, soaking sample in sodium hydroxide solution to remove residual zinc oxide, washing with deionized water and drying.    USE - The method is useful for preparing heterojunction photoelectrode of photoelectrochemical cell using semiconductor nanocomposite material (claimed).    ADVANTAGE - The method ensures simple preparation of heterojunction photoelectrode of photoelectrochemical cell using semiconductor nanocomposite material with high yield and improved photoelectric conversion efficiency and water photolysis efficiency.    DETAILED DESCRIPTION - Preparation of a heterojunction photoelectrode of photoelectrochemical cell using semiconductor nanocomposite material involves (a) synthesizing alpha -iron oxide nanorods by ultrasonically cleaning a conductive substrate with alcohol, acetone and deionized water, respectively, for 15 minutes, uniformly mixing ferric chloride hexahydrate, urea and ammonium fluoride to obtain aqueous solution, placing 10 ml aqueous solution in 20 ml PTFE-lined autoclave, placing cleaned conductive substrate at bottom of autoclave liner, heating autoclave at 120 degrees C, reacting for 6 hours, cooling to room temperature, removing samples, washing samples with deionized water and alcohol, drying using air at 80 degrees C for 2 hours, sintering using a muffle furnace at 550 degrees C for 2 hours and again sintering at 750 degrees C for 15 minutes, and (b) preparing alpha -iron oxide nanorods and zinc ferrite composite by placing alpha -iron oxide nanorods sample in 200 degrees C atomic layer deposition system in a reaction chamber, adding diethyl zinc as zinc source and water as oxygen source, depositing zinc oxide on alpha -iron oxide nanorods sample, placing the sample in a muffle furnace, sintering and annealing at 550 degrees C for 10 hours, cooling to room temperature, removing sample, soaking sample in 1 mole/l sodium hydroxide solution for 10 hours to remove residual zinc oxide, washing with deionized water and drying.