Using hollow dodecahedral NiCo-LDH with multi-active sites to modify BiVO ₄ photoanode facilitates the photoelectrochemical water splitting performance

Abstract

Photoelectrochemical (PEC) water splitting presents a promising approach for harnessing solar energy and converting it into hydrogen energy. However, the limited water oxidation activity of semiconductor photoanodes has severely hampered the overall conversion efficiency. In this study, a hollow dodecahedral structure of NiCo-LDH (HD-NiCo-LDH) was designed using the metal-organic framework ZIF-67 as a precursor. HD-NiCo-LDH was employed to modify the BiVO₄ photoanode, serving as an oxygen evolution cocatalyst. HD-NiCo-LDH can enhance light absorption, accelerate photogenic hole extraction, promote photogenic charge separation and improve the kinetics of water oxidation reaction. Significantly, the unique hollow dodecahedral structure of HD-NiCo-LDH possesses a larger specific surface areas, which provides additional active sites for the water oxidation reaction and facilitates the adsorption of water molecules. The photocurrent density of the optimized HD-NiCo-LDH/BiVO₄ photoanode reaches 4.54 mA/cm² at 1.23 V vs. RHE, which is 3.3 times greater than the bare BiVO₄ photoanode. This presented work introduces an innovative design concept for photoanodes supported by oxygen evolution cocatalysts with multi-active sites.