Piezocatalysis, a newly emerging catalysis technology that relies on the piezopotential and piezoelectric properties of the catalysts, is attracting unprecedented research enthusiasm for applications in energy conversion, organic synthesis, and environmental remediation. Despite the rapid development in the past three years, the mechanism of piezocatalysis is still under debate. A fundamental understanding of the working principles of this technology should enable the future design and optimization of piezocatalysts. Herein, we provide an overview of the two popular theories used to explain the observed piezocatalysis: energy band theory and screening charge effect. A comprehensive discussion and clarification of the differences, relevance, evidence, and contradiction of the two mechanisms are provided. Finally, challenges and perspectives for future mechanistic studies are highlighted. Hopefully, this Review can help readers gain a better understanding of piezocatalysis and enable its application in their own research.

Selective oxidation of benzyl alcohol (BzOH) into benzaldehyde (BzH) is very important in synthetic chemistry. Peroxymonosulfate (PMS) is a cheap, stable, and soluble solid oxidant, holding promise for organic oxidation reactions. Herein, we report the catalytic PMS activation via carbon nanotubes (CNTs) for the selective oxidation of BzOH under mild conditions without other additives. A remarkable promotion of BzH yield with a selectivity over 80% was achieved on modified CNTs, i.e., O-CNTs via the radical oxidation process, and the oxygen functionalities for catalysis were comprehensively investigated by experimental study and theoretical exploration. To understand the different surface oxygen species on CNTs for the activation of PMS, density functional theory (DFT) calculations were performed to investigate the adsorption behavior of PMS on various CNTs. The electrophilic oxygen was identified as the electron captor to activate PMS by O−O bond cleavage to form SO 5•− and SO 4 •− radicals. The nucleophilic carbonyl groups can also induce a redox cycle to generate • OH and SO 4•− radicals, but phenolic hydroxyl groups impede the radical process with antioxidative functionality. The carbocatalysis-assisted PMS activation may provide a cheap process for the selective oxidation of alcohols into aldehydes or ketones. The insight achieved from this fundamental study may be further applied to other organic syntheses via selective oxidation.

The development of highly efficient strategy for the activation C-H bond in hydrocarbons for organic synthesis is one of the most challenging tasks facing the chemical industries. Novel catalyst with...

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202004579.heterogeneous catalysis has received more attention recently due to the merits of easy separation/recycling and achieving green reaction process. [3] Precious metals such as platinum, ruthenium, gold, and palladium are found to afford excellent catalytic activity for the selective oxidation of alcohols, [2a,4] however, their scarcity and high cost hinder the real applications for chemical industry. As an alternative, the catalysts based on earth-abundant transition metals are investigated to activate different oxidants including molecular oxygen, ozone, and liquid peroxides (i.e., hydrogen peroxide and tert-butylhydroperoxide) for oxidative applications. [5] The particle size and dispersion of the metal/ metal oxides play a pivotal role in affecting the catalytic performance. Therefore, much attention has been focused on reducing the particle size and optimizing the coordination between the metals and supports. Graphene based materials are extensively studied as substrate to support highly dispersed metal particles owing to the high surface area and excellent chemical/electrochemical properties. [6] Single-atom catalysts (SACs) consist of individual atoms dispersed on and/or bonded with the surface atoms of an appropriate support with high selectivity, catalytic activity and excellent atomic efficiency. [7] The catalysts with supported

Artesunate (ART) is the derivative of artemisinin isolated from the traditional Chinese medicine qinghao. Although several studies reported the efficiency of artesunate in the treatment of malaria, inhibiting fibroblasts and collagen synthesis, the association between artesunate and scar formation is unclear. The research was designed to study the significance of artesunate (ART) on the expression of transforming growth factor (TGF-β1) and small mother against decapentaplegic (SMAD3) in rabbit's ear hypertrophic scar model. Twenty-four New Zealand white rabbits were randomly divided into six groups: control group, matrix group, low-concentration artesunate group (0.48%), medium-concentration artesunate group (0.96%), high-concentration artesunate group (1.92%) and silicone gel group. Punched defects were established on each rabbit’s ear which resulted in a hypertrophic scar. On the 28th day, topical artesunate creams were applied twice a day except on the control group. On the 56th day, scar samples were collected for histopathology and immunoassay. Hematoxylin and eosin staining, Van Gieson staining, immunohistochemistry and Western blot analysis were done. Amongst the six groups, findings showed that the medium-concentration artesunate group (0.92%) efficiently decreased hypertrophic scar formation and significantly reduced fibroblasts and collagen synthesis. The results had also shown a decrease in the expression of transforming growth factor (TGF-β1) and declined small signal mother against decapentaplegic (Smad3). The overall study shows efficacy and mechanism of artesunate. It concluded that the medium concentration of artesunate (0.92%) could be an effective therapeutic agent for hypertrophic scars.

Nanocarbon materials are promising catalysts of oxidative dehydrogenation (ODH) of alkanes, but improving the alkene selectivity remains a challenge. A deep understanding and thorough identification of oxygen species on nanocarbons are strongly required for approaches to nanocarbon modification. Successful application of iodometric titration in quantitative determination of the amount of electrophilic oxygen on the surface of carbon nanotubes has been performed in this work. Electrophilic oxygen species have been identified as the main culprits for deep oxidation of ODH of n-butane via a clear correlation between the amount of electrophilic oxygen and combustion reaction rate. By chemical reduction and annealing in nitrogen, the alkene selectivity is significantly improved. Phenol groups are found to play an essential role in improving alkene selectivity. The study reveals that higher alkene selectivity can be achieved by both eliminating deep oxidation active sites and facilitating the formation of phenol and carbonyl groups.

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