Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan.
Earth-Life Science Institute, Tokyo Institute of Technology, 152-8550 Tokyo, Japan.
Proc Natl Acad Sci U S A. 2020 Dec 15;117(50):31631-31638. doi: 10.1073/pnas.2008429117. Epub 2020 Nov 30.
Molybdenum sulfide (MoS) is the most widely studied transition-metal dichalcogenide (TMDs) and phase engineering can markedly improve its electrocatalytic activity. However, the selectivity toward desired products remains poorly explored, limiting its application in complex chemical reactions. Here we report how phase engineering of MoS significantly improves the selectivity for nitrite reduction to nitrous oxide, a critical process in biological denitrification, using continuous-wave and pulsed electron paramagnetic resonance spectroscopy. We reveal that metallic 1T-MoS has a protonation site with a p of ∼5.5, where the proton is located ∼3.26 Å from redox-active Mo site. This protonation site is unique to 1T-MoS and induces sequential proton-electron transfer which inhibits ammonium formation while promoting nitrous oxide production, as confirmed by the pH-dependent selectivity and deuterium kinetic isotope effect. This is atomic-scale evidence of phase-dependent selectivity on MoS, expanding the application of TMDs to selective electrocatalysis.
二硫化钼（MoS）是研究最为广泛的过渡金属二硫属化物（TMDs）之一，而相工程可以显著提高其电催化活性。然而，对于目标产物的选择性仍然研究甚少，限制了其在复杂化学反应中的应用。在这里，我们报告了相工程如何通过连续波和脉冲电子顺磁共振波谱显著提高亚硝酸盐还原为一氧化二氮的选择性，这一氧化二氮还原是生物反硝化过程中的一个关键步骤。我们揭示了金属 1T-MoS 具有一个 p 值约为 5.5 的质子化位点，其中质子距离氧化还原活性 Mo 位约 3.26 Å。这个质子化位点是 1T-MoS 所特有的，它诱导了顺序质子-电子转移，抑制了铵的形成，同时促进了一氧化二氮的生成，这一点通过 pH 依赖性选择性和氘动力学同位素效应得到了证实。这是 MoS 相依赖性选择性的原子尺度证据，扩展了 TMDs 在选择性电催化中的应用。
