Unraveling the nature of local field distortion-induced dual electron-trapping centers for efficient photocatalytic fuel evolution

Active electron-trapping centers play significant roles in photocatalysis. Herein, we synergize local field distortion and defects in nanocrystals to produce dual electron-trapping centers and unravel the nature of aluminum doping in porous ZnO with tunable amounts of heteroatoms and oxygen vacancies. The introduced Al atoms in the structural domain induce local field distortion and trigger the movement of Zn2+ from a singlet low spin state to a stable triplet state, resulting in the generation of free carriers trapping centers and optimized electronic energy band structure. Dual active electron-trapping centers of heteroatoms and oxygen vacancies promote the Separation of photo-generated charge carriers and reduce the adsorption energies of H* species. Furthermore, the d-band center of Al-doped ZnO with oxygen vacancies shifts to a higher energy position, thus promoting the adsorption and desorption of hydrogen intermediates and exhibiting 4-fold the photocatalytic H2 efficiency of pristine ZnO. This study provides new insights into the rational design of highly efficient oxide-based photocatalysts toward sustainable solar fuel evolution.