Vertical Growth of O-Vacancy Rich LDH Atomic Layers as OER-Sensitive Reactive Sites to Boost Overall Water Splitting on Perovskite Oxides

Dominating the abundance of active sites of photocatalysts and regulating the oxygen evolution reaction (OER) are the most desired but challenging technologies for photocatalytic overall water splitting. Herein, we demonstrate that O-vacancy-rich NiCo-LDH atomic layers (denoted Vo-LDH) featuring an exposed (001) facet grow vertically on perovskite oxide cubes (e.g., Al-CaTiO3 and Al-SrTiO3), which can provide multiaccessible OER-sensitive active sites to boost the overall water splitting performance. As a result, the overall water splitting production rate on the Al-CaTiO3/Vo-LDH (44%) catalyst (H2: 1.01 mmol·g-1·h-1 and O2: 0.46 mmol·g-1·h-1) is 2.37 times higher than that of the pristine Al-CaTiO3 catalyst. Meanwhile, the overall water-splitting production rate on the Al-SrTiO3/Vo-LDH (44%) catalyst (H2: 0.90 mmol·g-1·h-1 and O2: 0.37 mmol·g-1·h-1) is 2.08 times that of the pristine Al-SrTiO3 catalyst. In situ diffuse reflection infrared Fourier transform spectroscopy reveals that the O-vacancy-rich NiCo-LDH atomic layers can serve as the OER-sensitive active sites and vary with the O-vacancy concentration. The kinetic analysis further confirms that the O-vacancy-induced water decomposition (1612 cm-1) is the most dominant OER configuration on NiCo-LDH atomic layers. Furthermore, density functional theory (DFT) indicates that O-vacancies on NiCo-LDH atomic layers lower the energy barriers of OER steps.