Electrochemical reduction of CO₂ to value‐added products is an important and challenging reaction for sustainable energy study. Herein, bismuth nanosheets with thickness of around 10 nm were prepared through the electrochemical reduction of Bi³⁺. Ultrathin Bi nanosheets with numerous low‐coordination sites can efficiently reduce CO₂ to formate in aqueous solution. Within the potential range of −0.9 to −1.2 V vs. reversible hydrogen electrode (RHE), the faradaic efficiency of formate is over 90 %, outperforming many Bi catalysts. At −0.7 V, the Bi nanosheets exhibit much higher current for formate generation than that of bulk Bi, attributed to a high surface area and also modified intrinsic electronic properties brought about by the ultrathin structure. DFT calculations demonstrate that Bi nanosheets have much higher density of states at the Fermi level compared to bulk Bi, favoring improved CO₂ reduction on Bi nanosheets. At −1.0 V, Bi nanosheets exhibit high selectivity for formate and excellent stability during 5 h of electrolysis.

中文翻译：

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超薄铋纳米片作为高效的二氧化碳还原电催化剂

用电化学方法将CO ₂还原为增值产品是可持续能源研究的重要且具有挑战性的反应。在此，通过Bi ³⁺的电化学还原，制备了厚度约10nm的铋纳米片。具有许多低配位位点的超薄Bi纳米片可以有效减少CO ₂在水溶液中形成甲酸盐。在相对于可逆氢电极（RHE）的-0.9至-1.2 V的电势范围内，甲酸的法拉第效率超过90％，优于许多Bi催化剂。在-0.7 V时，Bi纳米片的甲酸生成电流要比块状Bi的高得多，这归因于高表面积以及超薄结构带来的固有电子特性的改变。DFT计算表明，与块状Bi相比，Bi纳米片在费米能级上具有高得多的状态密度，这有利于Bi纳米片改善CO _2的还原。在-1.0 V下，Bi纳米片在5 h的电解过程中表现出较高的甲酸选择性和出色的稳定性。