Gradient band alignment of N-doped titania nanosheets on TiO2 nanorod arrays for improved solar water oxidation

TiO2 is a typical semiconducting material for photoelectrochemical (PEC) hydrogen generation, but still suffers from poor light capturing capability and slow surface water oxidation kinetics. Herein, a homologous heterojunction has been designed and fabricated based on TiO2 nanorod arrays (NAs) and N-doped titania (Ti0.91O2-xNx) nanosheets (TON NSs). Owing to the narrower band gap, TON broadens light absorption range and enhances absorption intensity. More importantly, the employment of TON for interfacial modulation could accelerate the surface water splitting kinetics due to the gradient band alignment of TON/TiO2. The upshifted valence band could better drive the holes to travel across the surface of photoanode for water oxidation reaction. Consequently, the optimal TON/TiO2 photoanode has achieved a significantly improved photocurrent of 1.62 mA/cm2 at 1.23 V vs RHE, which is 2.45 times of that of TiO2. This work provides an effective strategy for the design and construction of homologous heterojunctions for energy catalytic re-actions.(c) 2022 Elsevier B.V. All rights reserved.