Efficient Ni(OH)<sub>2</sub>/WO<sub>3</sub> Photoanode for Photoelectrocatalytic Water Splitting at Low Bias
Yuli Ma, Yun Hang Hu
Abstract
A low onset potential and a high photocurrent of a photoanode are critical for efficient water splitting and energy saving in photoelectrochemical (PEC) systems. Herein, we report an efficient strategy to achieve a more negative onset potential for PEC water splitting. Namely, Ni(OH)2 was exploited to tune a WO3 photoanode, shifting the onset potential to the negative direction by more than 300 mV under AM 1.5G simulated sunlight, which is better than most reported WO3-based anodes. Consequently, its photocurrent density was greatly enhanced from 0 to 1 mA/cm2 at a low applied potential of 0.2 V vs Ag/AgCl (0.8 V vs a reversible hydrogen electrode, RHE). The negative shift of the onset potential in PEC water splitting was attributed to the large band bending and efficient charge transfer at the Ni(OH)2/WO3 interface at low bias. Furthermore, Ni(OH)2 can also promote H2O adsorption on the Ni(OH)2/WO3 electrode.