Introducing oxygen vacancies into metal oxides is a promising strategy to promote their catalytic activity, which has been extensively studied in heterogeneous catalysis. Herein, transition metal (M = Fe, Co, and Ni) doping was used to introduce oxygen vacancies in CeO 2 and promote activity for carbonyl sulfide (COS) hydrolysis. Various techniques were performed to accurately characterize the catalyst structure and state. The transition metals successfully entered the crystal lattice of CeO 2 and formed a solid solution structure. The metal-doped CeO 2 (M/CeO 2 ) showed improved reduction properties, more Ce 3+ and oxygen vacancies in comparison with pure CeO 2 . The introduction of transition metal greatly enhanced activity of M/CeO 2 for COS hydrolysis. Among them, the Co/CeO 2 sample displayed the highest activity and H 2 S selectivity. The roles of metal doping in improving activity were explored on the basis of DFT calculations. The strong interaction between doped metals and CeO 2 promotes the spontaneous formation of asymmetric oxygen vacancies in M/CeO 2 . These asymmetric oxygen vacancies facilitate the activation and dissociation of H 2 O and generation of active hydroxyls, which contributes to the enhanced activity for COS hydrolysis. This work provides an attractive method for obtaining nonprecious metal catalysts for COS hydrolysis.

The development of low-cost multifunctional electrocatalysts with high activity for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is critical for the advancement of sophisticated energy conversion and storage devices. Herein, a trifunctional Ni(S 0.51 Se 0.49 ) 2 @NC catalyst is designed and fabricated using a dianionic regulation strategy. Synchrotron radiation X-ray absorption spectroscopy and density functional theory calculations reveal that simultaneous sulfidation and selenization can induce the electronic delocalization of Ni(S 0.51 Se 0.49 ) 2 active sites to enhance the adsorption of *OOH/*OH intermediate for ORR/OER and H* intermediate for HER. The OER and HER mechanisms are revealed by in situ Raman spectroscopy. The Ni(S 0.51 Se 0.49 ) 2 @NC exhibits trifunctional catalytic activity for the HER (111 mV at 10 mA cm −2 ), OER (320 mV at 10 mA cm −2 ), and ORR (half-wave potential of 0.83 V). The rechargeable zinc-air batteries (ZABs) exhibit an open-circuit voltage of 1.46 V, a specific capacity of 799.1 mAh g −1 , and excellent stability for 1000 cycles. The water electrolytic cell using Ni(S 0.51 Se 0.49 ) 2 @NC electrodes delivers a current density of 10 mA cm −2 at a cell voltage of 1.59 V, and it can be powered using the constructed ZABs. These findings contribute to developing low-cost and efficient non-noble metal multifunctional catalysts.

The formation process and product control are very important in material synthesis. In this study, a facile one-pot hydrothermal method was used to prepare Co3O4 and CoOOH. H2O2 was used to modulate the formation process and control the final product by changing its concentration. The crystalline structures and morphologies of the as-prepared products were characterized by X-ray diffraction (XRD), Raman spectra, and scanning electron microscopy (SEM) techniques. It was found that the concentration of H2O2 influenced not only the phase of the final products but also their morphologies. The influences of H2O2 concentration on the precursor formation and the reaction path have been revealed. At a low concentration of H2O2 (5 wt %), the formed precursor is Co­(CO3)0.5(OH)·0.11H2O, which can be directly transformed into Co3O4 upon increasing the hydrothermal time. At a medium concentration (15–20 wt %), the formed precursor and the final product are all CoOOH. At a high concentration (30 wt %), the formed precursor is CoOOH, and the final product is Co3O4. H2O2 plays the role of oxidant agent at the initial stage or reducing agent at the subsequent stage. This study offers a H2O2-concentration modulating method for the formation of Co3O4 and CoOOH.