Defect-Rich NiO Nanosheet for Promoting Electrocatalytic OER and Oxidation of Chiral 2-Butanol

In this work, we prepared cubic nickel oxide (NiO) nanosheets and constructed NiO with oxygen defects induced by halogen Cl ions (NiO-Vo1). Cubic nickel oxide nanosheets were used as catalysts for electrocatalytic oxygen evolution reaction (OER) and oxidation of chiral 2-butanol. Under artificial simulated sunlight, NiO-Vo1 exhibited good photo-electrocatalytic OER activity and catalytic stability. The high catalytic activity is mainly attributed to the activation of nickel active sites by the halide ion-induced oxygen defect and the enhancement of photoinduced electron–hole separation efficiency. Furthermore, the electrocatalytic performance of oxygen-deficient nickel oxide for the oxidation of chiral 2-butanol was investigated. The results show the catalytic activity of NiO-Vo1 for electrocatalytic oxidation of 2-butanol to butanone compared with NiO. Interestingly, there is no significant difference in the electrocatalytic activity of NiO for (R)-(-)-2-butanol and (S)-( +)-2-butanol oxidation. When NiO-Vo1 was used as the catalyst, the catalytic oxidation reaction rate of (R)-(-)-2-butanol alcohol was significantly higher than that of (S)-( +)-2-butanol alcohol. At 1.77 V vs RHE voltage, the (R)-(-)-2-butanol alcohol has obvious oxidation reaction while the (S)-( +)-2-butanol alcohol is almost absent, realizing the selective electrocatalytic oxidation of (R)-(-)-2-butanol alcohol. This may be attributed to the difference in the interaction strength of chiral molecules with the surface defects of NiO after applying a voltage during the catalytic process, resulting in different catalytic activities. Here, our proposed strategy through the synergistic effect of applied voltage and surface defects provides a new approach for chiral molecule synthesis and efficient chiral resolution. The halide ion-induced defect-catalyst provides a new strategy for the preparation of efficient electrocatalytic water splitting OER and alcohol-selective oxidation catalysts. Graphical Abstract