Semiconductor photocatalysis driven by electron/hole has begun a new era in the field of solar energy conversion and storage. Here we report the fabrication and optimization of TiO2/BDD p-n heterojunction photoelectrode using p-type boron doped diamond (BDD) and n-type TiO2 which shows enhanced photoelectrochemical activity. A p-type BDD was first deposited on Si substrate by microwave plasma chemical vapor deposition (MPCVD) method and then n-type TiO2 was sputter coated on top of BDD grains for different durations. The microstructural studies reveal a uniform disposition of anatase TiO2 and its thickness can be tuned by varying the sputtering time. The formation of p-n heterojunction was confirmed through I-V measurement. A remarkable rectification property of 63773 at 5 V with very small leakage current indicates achieving a superior, uniform and precise p-n junction at TiO2 sputtering time of 90 min. This suitably formed p-n heterojunction electrode is found to show 1.6 fold higher photoelectrochemical activity than bare n-type TiO2 electrode at an applied potential of +1.5 V vs SHE. The enhanced photoelectrochemical performance of this TiO2/BDD electrode is ascribed to the injection of hole from p-type BDD to n-type TiO2, which increases carrier separation and thereby enhances the photoelectrochemical performance.

We report simultaneous photoelectrocatalytic (PEC) glucose sensing and biohydrogen generation for the first time from the direct PEC oxidation of glucose at multifunctional and robust Cu2O-TiO2 photocatalysts. Striking improvement of 30% in overall H2 gas evolution (∼122 μmol h(-1) cm(-2)) by photoholes assisted glucose oxidation opens a new platform in solar-driven PEC biohydrogen generation.

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