Porphyrin-based metal–organic frameworks anchored with Cu species for highly efficient electrocatalytic CO2 reduction to CH4

The electrocatalytic carbon dioxide (CO₂) reduction into methane (CH₄) represents a promising strategy for sustainable carbon cycling. Nevertheless, this complex conversion, involving an eight-electron transfer process, faces significant challenges in achieving satisfactory catalytic activity and CH₄ selectivity for practical applications. Herein, we employed a facile solvothermal reaction strategy to anchor copper (Cu) atoms in the porphyrin-based metal–organic framework (PMOF) to construct Cu single-atom catalysts, named the Cu-PMOF catalyst. The good combination of highly accessible Cu active sites, optimized Cu loading, and a loose structure in the Cu-PMOF electrode significantly enhanced the electrocatalytic performance for the conversion of CO₂ to CH₄. The highest Faradaic efficiency of CH₄ reached 80.4% at a current density of −300 mA cm⁻² in 1 M potassium hydroxide electrolytes with a flow cell configuration. Moreover, this Cu-PMOF electrode achieved a maximum partial current density of −337.5 mA cm⁻² at a potential of −1.23 V versus reversible hydrogen electrode. Comprehensive experimental investigations revealed the Cu-PMOF electrode enabled a multi-step CO^₂ hydrogenation process, characterized by effective H₂O activation and the sequential transformation of CO^₂ into crucial intermediates, ultimately leading to the selective formation of CH₄.

电催化二氧化碳（CO₂）还原为甲烷（CH₄）是实现可持续碳循环的有效途径。然而，这使一个涉及8电子转移的复杂反应过程，在实际应用中实现高效催化和甲烷选择性生成仍面临巨大挑战。本文采用简便的溶剂热反应策略，将铜原子（Cu）锚定于卟啉基金属有机框架（porphyrin-based metal–organic framework，PMOF）中，构建出命名为Cu-PMOF的单原子铜催化剂。该Cu-PMOF电极具有高活性Cu反应位点、最优Cu负载量及疏松的结构，显著增强了还原CO₂为CH₄的电催化效率。在1 M氢氧化钾电解液流动电池体系中，当电流密度~300 mA·cm-2时，Cu-PMOF催化CH₄生成的最高法拉第效率可达80.4%。此外，在可逆氢电极电位为-1.23 V时，该Cu-PMOF电极的最大部分电荷密度可达-337.5mA·cm⁻²。以上实验结果表明，Cu-PMOF电极通过高效活化H2O并将CO2逐步转化为关键中间体的方式，实现了CO₂多步加氢过程并最终选择性生成CH₄。

期刊：Green Chemistry

原文链接：https://pubs.rsc.org/en/content/articlelanding/2025/gc/d5gc02085a/unauth