You Xu,Tianlun Ren,Shanshan Yu,Hongjie Yu,Shuli Yin,Ziqiang Wang,Xiaonian Li,Liang Wang,Hongjing Wang
The electrocatalytic nitrogen reduction reaction (NRR) for ammonia (NH3) synthesis is highly desirable yet still challenging. Catalysts, as the core component of electrocatalytic NRR systems, are a specific focus of research. In this work, we demonstrate that NRR active semimetal bismuth (Bi) ultrathin nanosheets (Bi NSs) could be prepared by means of the in situ electrochemical reduction-assisted exfoliation of BiOCl nanoplates (BiOCl NPs). Such a conversion, from semiconductive BiOCl NPs to semimetal Bi NSs, could create enlarged surface areas and bring about abundant under-coordinated Bi sites and accelerated electron transport capability. With these advantageous properties, the as-converted Bi NSs exhibit efficient NRR electrocatalytic activity in 0.1 M Na2SO4, achieving a high faradaic efficiency (14.14%) and NH3 yield (11.11 μg h−1 mgcat.−1) at −0.5 V (vs. reversible hydrogen electrode), as well as high NH3 selectivity.
Liu Jinze,Li Yuhang,Wang Yating,Xiao Chuqian,Liu Miaomiao,Zhou Xiaodong,Jiang Hao,Li Chunzhong
Electrochemical reduction of CO 2 to valuable formate as liquid fuel is a promising way to alleviate the greenhouse effect. The edge active sites in bismuth (Bi) nanosheets play a critical role in the electrochemical reduction of CO 2 into formate, which enable the operation of CO 2 reduction with high cathodic energy efficiency, especially under large current densities of ≥ 200 mA/cm 2 . However, the undesirable reconstruction of small Bi nanosheets into large nanosheets leads to the decreasing of edge active sites during electrocatalysis. Here we report stable isolated ultrasmall bismuth nanosheets-synthesized by in-situ electrochemical transformation of ligands covered bismuth vanadate-on silver nanowires as an efficient electrocatalyst for CO 2 -to-formate reduction. The cooperative electrocatalyst achieves a formate current density of 186 mA/cm 2 and a cathodic energy efficiency of 75% for formate, which is the only best compared to the literature results. Operando Raman and morphologic measurements demonstrate that the excellent energy utilization of the electrocatalyst is originated from the rich edge active sites with Bi-O species of the ultrasmall Bi nanosheets.
Fang Wei,Ting Luo,Yan Wang,Lichun Kong,JiuJu Feng,Zhengquan Li,Ji-Qing Lu,Fa Yang
A novel electrocatalyst for CO 2 -to-formate conversion at low overpotentials with abundant bimetallic interfaces aroused from Pd nanoparticles anchoring in the underlying Bi nanosheet (Pd-BiNS) was developed. This unique synthesis procedure undergoes a continuous reconstruction of Pd-BiOINS to Pd-Bi 2 O 2 CO 3 NS to Pd-BiNS, which was confirmed by in situ Raman spectra combined with quasi- in - situ electron microscopy. The optimized Pd 1 -BiNS exhibits a high Faradaic efficiency of 95 % for formate at only − 0.4 V versus reversible hydrogen electrode over 30 h electrolysis, breaking the limitation that metallic Pd-site is easily poisoned by the generated CO at low overpotentials. The in situ infrared spectroscopy indicates that Pd-BiNS has much suppressed *CO binding and enhanced *OCHO adsorption to inhibit the competing hydrogen evolution reaction by repelling surface water molecules, moreover, a systematic CO 2 RR mechanism with HCO 3 − participating as pre-proton donor for formate generation is unveiled. This work provides new insight into the multisite synergistic regulation at the atomic scale.
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