Ultrathin g-C3N4/Mo:BiVO4 photoanode for enhanced photoelectrochemical water oxidation

A g-C3N4/Mo:BiVO4 (CMB) heterojunction photoanode is constructed with enhanced photoelectrochemical (PEC) water oxidation performance, in which ultrathin g-C3N4 is coated on Mo-doped BiVO4. CMB shows a remarkable water oxidation photocurrent of 3.11 mA cm(-2) at 1.23 V vs. RHE, which is 3.21 times higher than pristine BiVO4. The maximal incident photon-to-current efficiency (IPCE) reaches 45.5% at 430 nm and the applied bias photo-to-current efficiency (ABPE) reaches 0.74% at 0.78 V vs. RHE, which are 2.62 and 5.76 times compared with pristine BiVO4, respectively. The amounts of hydrogen and oxygen generated by CMB are 18.58 and 9.32 mu mol within 1 h, which are 4.66 and 5.51 times higher than pristine BiVO4. The significant enhancements are attributed to the improvement of charge separation and acceleration of oxygen evolution reaction (OER) kinetics. Mo-dopant enhances charge separation due to its excellent electron transfer capability. Ultrathin g-C3N4 also boosts charge separation via forming a heterojunction with Mo:BiVO4 and promotes OER kinetics by accelerating the transfer of holes to the photoelectrode surface. The work testifies the promise of combing metal-doping with constructing heterojunctions using ultrathin g-C3N4 to enhance water oxidation performance, and provides an excellent reference for designing and constructing efficient photoanodes for PEC water oxidation.