Conducting oxide surface engineering enables growth of low-defect carbon nitride film for unbiased photoelectrochemical water splitting

Abstract

The favorable crystal surface exposure of substrate benefits the growth of semiconductor film with strong adhesion and fast charge transfer at the interface. Herein, exposure of (211) of SnO2:F (FTO) by surface etching led to uniform synthesis of crystalline carbon nitride (CN) film. The as-synthesized CN film shows preferable electron transfer from CN to FTO, low structural defects, and excellent charge separation and transport. It produces the state-of-art photovoltage of 0.64 V. Photoelectrochemical (PEC) water splitting investigation demonstrated excellent performance with low water oxidation onset potential of 0.22 V vs RHE, as well as impressive unbiased photocurrent of 12.4 μA cm-2. Cocatalyst of NiCo-LDH led to high photocurrent of 440 μA cm-2 in triethanolamine containing electrolyte, with H2 yield of 40.9 mmol m-2 h-1 and IPCE (400 nm) of 26.7%. This work demonstrates a good example for growth of high-quality CN film with high PEC performance enabled by substrate surface engineering, which would also expand CN film’s other applications.