Multiscale understand the tuning photocatalytic hydrogen evolution performances of BiOCl stemmed from engineered crystal facet

BiOCl photocatalyst has been extensively investigated due to unique internal electric field. However, the limited photocatalytic efficiency seriously blocks the further development of this photocatalyst. Here, using one-step hydrothermal process, we prepared the octagonal plate BiOCl, which is characterized with (1 1 0) facets. Contrasted with the ordinary BiOCl with (0 1 0) and (0 0 1) facets, the designed BiOCl-110 exbibits approximately 1.70 times and 3.15 times enhancement in photocatalytic H2 evolution, along with qualified reusability. The experimental findings collectively uncover the origin of high hydrogen production, which (1 1 0) facet greatly prolongs the lifetime of carriers, sharply increases the surface photovoltage and reasonably optimizes the carrier transport. Particularly, density functional theory simulations unveil a remarkably reduced transition between valence band maximum and conduction band minimum within BiOCl-110, resulting in a largely increased carrier extraction. Besides, the optimized free energy barriers of intermediates yield proper adsorption and desorption process in overall H2O splitting. Further ab initio molecular dynamics calculations unlock that the distinctive atomic structure on surface of the octagonal plate BiOCl serves as the inherent factor in regulating the element distribution of H2O layer on photocatalyst surface. The facet-dependent electronic structure and facet/H2O interface effects offer crucial understanding for BiOCl in highly effective hydrogen evolution.