电沉积过渡金属氧化物上甲烷电化学氧化成甲醇,Journal of the American Chemical Society

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电沉积过渡金属氧化物上甲烷电化学氧化成甲醇
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-03-21 , DOI: 10.1021/jacs.3c00441
Kangze Shen ₁ , Simran Kumari ₁ , Yu-Chao Huang ₁ , Joonbaek Jang ₁ , Philippe Sautet _{1,

2,

3} , Carlos G Morales-Guio ₁

Affiliation

将甲烷电化学部分氧化为甲醇是将搁浅的甲烷资源转化为高价值、易于运输的燃料或化学品的一种很有前途的方法。过渡金属氧化物是这种转化的潜在电催化剂。然而，尚未实现甲烷活化速率和甲醇选择性对催化剂形态和实验操作参数的依赖性的全面系统研究。在这里，我们描述了一种电化学方法，用于沉积一系列薄膜过渡金属（氧）氢氧化物作为甲烷部分氧化的催化剂。CoO _x、NiO _x、MnO _x和CuO _x发现对甲烷部分氧化成甲醇具有活性。服用 CoO _x作为原型甲烷部分氧化电催化剂，我们系统地研究了活性和甲醇选择性对催化剂膜厚度、过电位、温度和电化学电池流体动力学的依赖性。低催化剂膜厚度、中间超电势、中间温度和快速甲醇传输的最佳条件被确定为有利于甲醇选择性。通过控制实验和 DFT 计算的结合，我们表明沉积的（氧）氢氧化物催化剂膜的氧化形式即使在不施加偏置电位的情况下也对甲烷热氧化为甲醇具有活性，证明高价态转变金属氧化物对于在环境温度下将甲烷活化和氧化成甲醇具有内在活性。

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Electrochemical Oxidation of Methane to Methanol on Electrodeposited Transition Metal Oxides

Electrochemical partial oxidation of methane to methanol is a promising approach to the transformation of stranded methane resources into a high-value, easy-to-transport fuel or chemical. Transition metal oxides are potential electrocatalysts for this transformation. However, a comprehensive and systematic study of the dependence of methane activation rates and methanol selectivity on catalyst morphology and experimental operating parameters has not been realized. Here, we describe an electrochemical method for the deposition of a family of thin-film transition metal (oxy)hydroxides as catalysts for the partial oxidation of methane. CoO_x, NiO_x, MnO_x, and CuO_x are discovered to be active for the partial oxidation of methane to methanol. Taking CoO_x as a prototypical methane partial oxidation electrocatalyst, we systematically study the dependence of activity and methanol selectivity on catalyst film thickness, overpotential, temperature, and electrochemical cell hydrodynamics. Optimal conditions of low catalyst film thickness, intermediate overpotentials, intermediate temperatures, and fast methanol transport are identified to favor methanol selectivity. Through a combination of control experiments and DFT calculations, we show that the oxidized form of the as-deposited (oxy)hydroxide catalyst films are active for the thermal oxidation of methane to methanol even without the application of bias potential, demonstrating that high valence transition metal oxides are intrinsically active for the activation and oxidation of methane to methanol at ambient temperatures. Calculations uncover that electrocatalytic oxidation enables reaching an optimum potential window in which methane activation forming methanol and methanol desorption are both thermodynamically favorable, methanol desorption being favored by competitive adsorption with hydroxide anion.

更新日期：2023-03-21

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