Modification of an oxyhalide solid-solution photocatalyst with an efficient O 2 -evolving cocatalyst and electron mediator for two-step photoexcitation overall water splitting

• Published in: Nanoscale 2024-01, Vol.16 (4), p.1733-1741
• Main Authors: Sun, Wenzheng, Luo, Ying, Xu, Jun, Guo, Qiaoqi, Deng, Lidan, Wang, Zheng, He, Hong
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/D3NR05498E

Two-step photoexcitation overall water splitting based on particulate photocatalysts represents a promising approach for low-cost solar hydrogen production. The performance of an O -evolution photocatalyst and electron mediator between two photocatalysts crucially influences the construction of an efficient two-step excitation water-splitting system. Bismuth-tantalum oxyhalides are emerging photocatalysts for O evolution reactions and can be applied in two-step water-splitting systems. In this study, a highly crystalline Bi TaO Cl Br solid solution with microplatelet morphology was synthesized by the dual flux method. The light absorption intensity and charge transfer efficiency of the Bi TaO Cl Br solid solution were higher than those of Bi TaO Cl and Bi TaO Br; thus, the sacrificial O evolution activity of Bi TaO Cl Br photocatalyst was obviously enhanced. The two-step excitation water splitting with a solid-state electron mediator was successfully constructed using Bi TaO Cl Br as the O -evolution photocatalyst and Ru/SrTiO :Rh as the H -evolution photocatalyst. The CoO cocatalyst and reduced graphene oxide decorations on the surface of Bi TaO Cl Br promoted the catalytic O generation process on Bi TaO Cl Br and electron transfer between CoO /Bi TaO Cl Br and Ru/SrTiO :Rh photocatalysts, respectively. As a result, the apparent quantum yield for this overall water-splitting system was 1.26% at 420 nm, which surpassed the present performance of the two-step excitation water-splitting systems consisting of metal oxyhalide photocatalysts. This study demonstrates the validity of high-quality solid-solution photocatalysts with suitable surface modification for efficient solar hydrogen production from water splitting.