Conformal Macroporous Inverse Opal Oxynitride-Based Photoanode for Robust Photoelectrochemical Water Splitting

• Published in: Journal of the American Chemical Society Vol. 143; no. 19; pp. 7402 - 7413
• Main Authors: Ran, Lei, Qiu, Shi, Zhai, Panlong, Li, Zhuwei, Gao, Junfeng, Zhang, Xiaomeng, Zhang, Bo, Wang, Chen, Sun, Licheng, Hou, Jungang
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.05.2021
• Subjects: Carbon nitride; Carrier separation; circular dichroism; Critical challenges; crystal structure; Density functional theory; electrochemical analysis; energy conservation; Energy conversion; energy dispersive X ray spectroscopy; Heterojunctions; High current densities; hydrogen; Incident photon-to-current efficiencies; infrared spectroscopy; lighting; opal; oxidation; photocatalysis; Photoelectric devices; Photoelectrochemical cells; Photoelectrochemical water splitting; Photoelectrochemicals; photoelectrodes; photosynthesis; porous media; refraction index; renewable energy sources; Reversible hydrogen electrodes; scanning electron microscopy; Silicate minerals; spectroscopy; Tantalum compounds; Three-dimensional ordered macroporous; transmission electron microscopy; waste water management; X ray diffraction
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.1c00946

Direct photoelectrochemical (PEC) water splitting is of prime importance in sustainable energy conversion systems; however, it is a big challenge to simultaneously control light harvesting and charge transport for the improvement of PEC performance. Herein, we report a three-dimensional ordered macroporous (3DOM) CsTaWO6–x N x inverse opal array as a promising candidate for the first time. To address the critical challenge, an ultrathin carbon-nitride-based layer-intercalated 3DOM CsTaWO6–x N x architecture as a conformal heterojunction photoanode was assembled. This state-of-the-art conformal heterojunction photoanode with carrier-separation efficiency up to 88% achieves a high current density of 4.59 mA cm–2 at 1.6 V versus a reversible hydrogen electrode (vs RHE) under simulated AM 1.5G illumination, which is approximately 3.4 and 17 times larger than that of pristine CsTaWO6–x N x inverse opals and powers photoelectrodes in alkaline media, corresponding to an incident photon-to-current efficiency of 32% at 400 nm and outstanding stability for PEC water splitting. Density functional theory calculations propose that the intimate interface of a conformal photoanode optimizes the charge separation and transfer, thus enhancing the intrinsic water oxidation performance. This work enables us to elucidate the pivotal importance of 3DOM architectures and conformal heterostructures and the promising contributions to excellent PEC water-splitting applications.