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Electrochemical two‐electron oxygen reduction reaction (2 e− ORR) to produce hydrogen peroxide (H2O2) is a promising alternative to the energetically intensive anthraquinone process. However, there remain challenges in designing 2 e− ORR catalysts that meet the application criteria. Here, we successfully adopt a microwave‐assisted mechanochemical‐thermal approach to synthesize hexagonal phase SnO2 (h‐SnO2) nanoribbons with largely exposed edge structures. In 0.1 M Na2SO4 electrolyte, the h‐SnO2 catalysts achieve the excellent H2O2 selectivity of 99.99 %. Moreover, when employed as the catalyst in flow cell devices, they exhibit a high yield of 3885.26 mmol g−1 h−1. The enhanced catalytic performance is attributed to the special crystal structure and morphology, resulting in abundantly exposed edge active sites to convert O2 to H2O2, which is confirmed by density functional theory calculations. [ABSTRACT FROM AUTHOR]

Direct electrosynthesis of hydrogen peroxide (H2O2) via two‐electron pathway oxygen reduction reaction (2e− ORR) is crucially essential for a sustainable green economy. However, catalysts inevitably undergo four‐electron pathway oxygen reduction reaction (4e− ORR), resulting in low selectivity and economic benefits. The current challenge is to provide a feasible design strategy for obtaining satisfactory 2e− ORR catalysts with high selectivity. In this work, carbon dots (CDs) act as a cocatalyst to regulate the electron transport kinetics of In2O3/CDs, and the influence of CDs on the ORR pathways of In2O3/CDs is also studied. The electron transfer kinetics on In2O3/CDs composites are studied and analyzed using the transient photo‐induced voltage (TPV) technology. Combining the TPV results and kinetics analysis, it is shown that the electron transport on the In2O3 interface is obviously weakened after the addition of CDs, resulting in a high H2O2 selectivity. It is also demonstrated that CDs can effectively enhance the selectivity of H2O2, and the H2O2 selectivity of In2O3/CDs–10 is in close proximity to 100%, which is much higher than that of pure In2O3 (72%). This work will provide a new understanding and insight into addressing the challenge of low H2O2 selectivity for 2e− ORR catalysts. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cells (DEFCs) are considered as the ideal green power suppliers because of high energy density and non-toxicity of ethanol. Here the ball cactus-like gold (Au) particles reduced by hydrogen peroxide solution are coated with sulfhydryl-functionalized carbon dots (SCDs-Au). When the SCDs-Au composite is employed as the anodic electrocatalyst for ethanol oxidation reaction, an anode peak current density of 23.23 mA cm−2 (mass activity of 102.65 mA mg−1) is obtained at 0.19 V (vs. SCE) in 1.0 M KOH and 1.0 M ethanol at a scan rate of 20 mV s−1, which is about 4.4 times than that of Au without modification of SCDs. The higher catalytic activity is attributed to the higher ethanol adsorption capability caused by the shell-like SCDs. According to the adsorption experiment, ethanol adsorption capability of SCDs-Au is calculated as 2.8 times than that of Au without modification. At the same time, the addition of SCDs improves the electrocatalytic stability of Au. Such a surface modification method can be applied in other catalyst design processes. The ball cactus-like gold (Au) particles reduced by hydrogen peroxide solution are coated with sulfhydryl-functionalized carbon dots (SCDs-Au). SCDs-Au shows enhanced anode current density for ethanol oxidation attributed to the higher ethanol adsorption capability caused by CDs shell. [ABSTRACT FROM AUTHOR]