The realization of an efficient photocatalytic water splitting in the absence of sacrificial agent is an important step to achieve the sustainable production of hydrogen using solar energy. Heterostructure-based photocatalysts are used to mitigate charge recombination, thus leading to the improved photoactivity. In a traditional electrochemical system, it works similarly as the heterostructure of z-scheme type which transports the photoinduced electrons to the cathode. Herein, by using a photo-electrochemical process, the production of oxygen and hydrogen was achieved with improved photocatalytic faradaic efficiency. The oxygen evolution process (OER) was improved upon modifying the hematite with phosphorous. The phosphorous doping led to a shift of the band structure toward more positive potentials, resulting in higher OER rates. The optimized electrode achieved a plateau photocurrent of 2.5 mA/cm(2) at 100 mW/cm(2) illumination.