Developing a reliable strategy for the modulation of the texture, composition, and electronic structure of electrocatalyst surfaces is crucial for electrocatalytic performance, yet still challenging. Herein, we develop a facile and universal strategy, quenching, to precisely tailor the surface chemistry of metal oxide nanocatalysts by rapidly cooling them in a salt solution. Taking NiMoO 4 nanocatalysts an example, we successfully produce the quenched nanocatalysts offering a greatly reduced oxygen evolution reaction (OER) overpotential by 85 mV and 135 mV at 10 mA cm −2 and 100 mA cm −2 respectively. Through detailed characterization studies, we establish that quenching induces the formation of numerous disordered stepped surfaces and the near-surface metal ions doping, thus regulating the local electronic structures and coordination environments of Ni, Mo, which promotes the formation of the dualsite active and thereby affords a low energy pathway for OER. This quenching strategy is also successfully applied to a number of other metal oxides, such as spinel-type Co 3 O 4 , Fe 2 O 3 , LaMnO 3 , and CoSnO 3 , with similar surface modifications and gains in OER activity. Our finding provides a new inspiration to activate metal oxide catalysts and extends the use of quenching chemistry in catalysis.

Volatile organic compounds (VOCs) are one of the main sources of air pollution, which are of wide concern because of their toxicity and serious threat to the environment and human health. Catalytic oxidation has been proven to be a promising and effective technology for VOCs abatement in the presence of heat or light. As environmentally friendly and low-cost materials, manganese-based oxides are the most competitive and promising candidates for the catalytic degradation of VOCs in thermocatalysis or photo/ thermocatalysis. This article summarizes the research and development on various manganesebased oxide catalysts, with emphasis on their thermocatalytic and photo/thermocatalytic purification of VOCs in recent years in detail. Single manganese oxides, manganese-based oxide composites, as well as improving strategies such as morphology regulation, heterojunction engineering, and surface decoration by metal doping or universal acid treatment are reviewed. Besides, manganese-based monoliths for practical VOCs abatementare also discussed. Meanwhile, relevant catalytic mechanisms are also summarized. Finally, the existing problems and prospect of manganese-based oxide catalysts for catalyzing combustion of VOCs are proposed.

Most research studies reported that oxygen vacancies on transition metal oxides are crucial for improving the catalytic oxidation activities. However, few studies investigated the coexistence effect of metal defects and oxygen vacancies on the performances and mechanisms of catalysts. Herein, we present a facile approach for synthesizing a Co3–x O4–y catalyst with both cobalt defects and oxygen vacancies simultaneously, exhibiting significant thermo-/photothermo-catalytic performance for toluene oxidation (300 ppm, GHSV = 72,000 mL g–1 h–1) with over 90% toluene conversion in 10 min of light illumination (with a corresponding light-to-heat conversion temperature of ∼180 °C). Furthermore, the synchrotron radiation X-ray absorption spectroscopy, O2 temperature-programmed desorption, and density functional theory calculations demonstrate that cobalt defects are conducive to the formation of oxygen vacancies. In situ DRIFTS studies reveal that the as-formed surface-reactive oxygen species can be replenished continuously during the reaction progress, and the coexisting oxygen vacancies can accelerate the conversion of intermediates, thereby promoting the toluene degradation.

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