Three-dimensional ordered porous N-doped carbon-supported accessible Ni-N<subscript>x</subscript> active sites for efficient CO<subscript>2</subscript> electroreduction.

Electrocatalytic reduction of carbon dioxide (CO 2 RR) into high value-added chemicals and fuels has been regarded as a promising approach to achieve carbon neutrality. Though nickel-nitrogen-carbon (Ni-N-C) electrocatalysts have shown superior CO 2 RR performance, the synthesis of highly effective Ni-N-C catalyst is still challenging. Herein, a three-dimensional (3D) ordered porous nitrogen-doped carbon-supported Ni-N x catalyst has been synthesized by direct pyrolysis of a mixture of SiO 2 , polyvinyl pyrrolidone, nickel-phenanthroline complex, followed by the removal of the SiO 2 templates. Benefiting from the porous structure and accessible active sites, the optimized catalyst exhibits a high CO Faradaic efficiency above 85% between –0.6 and –0.9 V versus reversible hydrogen electrode (vs. RHE), and a large CO current density (j CO ) of –16.2 mA·cm −2 at –0.8 V (vs. RHE). Density functional theory (DFT) calculations demonstrate that the Ni-N-C catalyst with Ni-N x species can enhance CO 2 RR reaction dynamic process and suppress hydrogen evolution reaction, thus improving the conversion efficiency toward CO 2 RR. [ABSTRACT FROM AUTHOR]

摘要: 电催化还原二氧化碳（CO 2 RR）为高附加值的化学品和燃料，是实现碳中和的一个有前景的途径。尽管镍-氮-碳 （Ni-N-C）电催化剂已显示出不错的二氧化碳还原性能，但高效的Ni-N-C 催化剂的合成仍然是一个挑战。在此，通过直接热解二氧化硅、聚乙烯吡咯烷酮、镍-菲罗啉复合物的混合物，然后去除二氧化硅模板，合成了一种Ni-N x 位点锚定的三维（3D）有序多孔的氮掺杂碳支撑的电催化剂。受益于多孔结构和可利用的活性位点，优化后的 催化剂在‒0.6 至‒0.9 V（vs. RHE）之间表现出85%以上的高CO 法拉达效率，并且在‒0.8V 下， CO 电流密度 （jCO），达到‒16.2 mA·cm -2 。密度泛函理论（DFT）计算表明，含有Ni-Nx 位点锚定的Ni-N-C 催化剂可以促进 CO 2 RR 过程，同时抑制析氢反应，从而提高CO 2 RR 催化性能。 [ABSTRACT FROM AUTHOR]

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