Electrocatalytic two‐electron reduction of oxygen is a promising method for producing sustainable H2O2but lacks low‐cost and selective electrocatalysts. Here, the Chevrel phase chalcogenide Ni2Mo6S8is presented as a novel active motif for reducing oxygen to H2O2in an aqueous electrolyte. Although it has a low surface area, the Ni2Mo6S8catalyst exhibits exceptional activity for H2O2synthesis with >90% H2O2molar selectivity across a wide potential range. Chemical titration verified successful generation of H2O2and confirmed rates as high as 90 mmol H2O2gcat−1h−1. The outstanding activities are attributed to the ligand and ensemble effects of Ni that promote H2O dissociation and proton‐coupled reduction of O2to HOO*, and the spatial effect of the Chevrel phase structure that isolates Ni active sites to inhibit OO cleavage. The synergy of these effects delivers fast and selective production of H2O2with high turn‐over frequencies of ≈30 s−1. In addition, the Ni2Mo6S8catalyst has a stable crystal structure that is resistive for oxidation and delivers good catalyst stability for continuous H2O2production. The described Ni‐Mo6S8active motif can unlock new opportunities for designing Earth‐abundant electrocatalysts to tune oxygen reduction for practical H2O2production.
Direct synthesis of hydrogen peroxide (H2O2) from H2and O2on a Pd‐based catalyst has emerged as a promising route to replace the energy‐consuming, highly inefficient anthraquinone process. However, Pd is also a good catalyst for the decomposition of H2O2, thereby compromising the selectivity toward the desired product. The coupling between the formation and decomposition reactions makes it difficult to single out the most important parameter that controls the selectivity toward direct synthesis of H2O2. Herein, support‐free monometallic Pd nanocrystals with different shapes and surface strains are used to investigate their impacts on the decomposition kinetics of H2O2. The kinetics are analyzed by tracking the concentration of the remaining H2O2using infrared spectroscopy. The data indicates that both surface structure and strain affect the decomposition kinetics of H2O2, but their impacts are inferior to that caused by Br−, a surface capping agent for the Pd{100} facets. The experimental results are consistent with the trend obtained through density functional theory calculations. This work helps shed light on the development of Pd‐based catalysts for the direct synthesis of H2O2by offering strategies to mitigate the decomposition of the desired product.
more » « less- PAR ID:
- 10371548
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemCatChem
- Volume:
- 14
- Issue:
- 16
- ISSN:
- 1867-3880
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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