Abstract

Developing efficient carbon-based metal-free electrocatalysts can bridge the gap between laboratory studies and practical applications of CO₂ reduction. However, along with the ambiguous understanding of the active sites in carbon-based electrocatalysts, carbon-based electrocatalysts with high selectivity and satisfactory stability for electroreduction of CO₂ remain rare. Here, using the nitrogen rich silk cocoon as a precursor, carbon-based electrocatalysts with intrinsic defects can be prepared for efficient and long-term electroreduction of CO₂ by a simple two-step carbonization. The obtained electrocatalyst can catalyze CO₂ reduction to CO with a Faradaic efficiency of ~ 89% and maintain good selectivity for about 10 days. Particularly, our experimental studies suggest that in-plane defects are the main active sites on which the rate-determining step for CO₂ reduction should be the direct electron transfer to CO₂ but not the proton-coupled electron transfer. Further theoretical calculations consistently demonstrate that the intrinsic defects in carbon matrix, particularly the pentagon-containing defects, act as main active sites to accelerate the direct electron transfer for CO₂ reduction. In addition, our synthetic approach can convert egg white into efficient catalysts for CO₂ electroreduction. These findings, providing new insights into the biomass-derived catalysts, should pave the way for fabricating efficient and stable carbon-based electrocatalysts with catalytically active defects by using naturally abundant precursors.

中文翻译：

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生物质衍生碳中的固有缺陷促进了CO 2的电还原

摘要

开发有效的基于碳的无金属电催化剂可以弥合实验室研究与减少CO _2的实际应用之间的差距。然而，随着对碳基电催化剂中的活性位点的模糊理解，对于CO _2的电还原具有高选择性和令人满意的稳定性的碳基电催化剂仍然很少。在此，使用富氮蚕茧作为前体，可以制备具有固有缺陷的碳基电催化剂，以通过简单的两步碳化有效且长期地电还原CO ₂。所获得的电催化剂可以催化CO _2。将法拉第效率降低至约89％，并保持良好的选择性约10天。特别地，我们的实验研究表明，平面缺陷是主要的活性位点，在该活性位点上，CO ₂还原速率的决定步骤应该是直接电子转移至CO ₂而不是质子耦合电子转移。进一步的理论计算一致地表明，碳基质中的固有缺陷，特别是含五边形的缺陷，充当主要活性位点，可加速直接电子转移以还原CO ₂。此外，我们的合成方法可以将蛋清转化为高效的CO ₂催化剂电还原。这些发现为生物质衍生的催化剂提供了新的见解，应为使用天然丰富的前体制备具有催化活性缺陷的高效稳定的碳基电催化剂铺平道路。