An Integrating Photoanode of WO3/Fe2O3 Heterojunction Decorated with NiFe-LDH to Improve PEC Water Splitting Efficiency

Combining semiconductor heterojunction and cocatalyst is an important strategy to improve photoelectrochemical (PEC) water splitting efficiency. Here, a photoanode of WO3/Fe2O3 heterojunction decorated by NiFe-layered double hydroxide (LDH) was fabricated by two-step hydrothermal methods. As expected, the photocurrent density of the ternary photoanode reaches up to 3.0 mA·cm–2, which respectively are 5 times and 7 times of WO3 and α-Fe2O3. The improvement benefits from the extending absorption of visible light, the effective separation of photogenerated charge carriers, and acceleration of water oxidizing reaction, which is caused by narrowing band gap and electron directionally flowing of heterojunction as well as catalyst timely consuming of holes accumulated at the electrode surface. The electron lifetime and the steady-state carrier density for four photoanodes were estimated from electrochemical impedance spectra (EIS) and were further confirmed by the intensity modulated photocurrent spectra (IMPS). The work provides a demonstration to develop a high efficiency and low-cost photoanode for application in solar energy PEC water splitting.