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Bismuth (Bi) has been known as a highly efficient electrocatalyst for CO2 reduction reaction. Stable free-standing two-dimensional Bi monolayer (Bismuthene) structures have been predicted theoretically, but never realized experimentally. Here, we show the first simple large-scale synthesis of free-standing Bismuthene, to our knowledge, and demonstrate its high electrocatalytic efficiency for formate (HCOO−) formation from CO2 reduction reaction. The catalytic performance is evident by the high Faradaic efficiency (99% at −580 mV vs. Reversible Hydrogen Electrode (RHE)), small onset overpotential (<90 mV) and high durability (no performance decay after 75 h and annealing at 400 °C). Density functional theory calculations show the structure-sensitivity of the CO2 reduction reaction over Bismuthene and thicker nanosheets, suggesting that selective formation of HCOO− indeed can proceed easily on Bismuthene (111) facet due to the unique compressive strain. This work paves the way for the extensive experimental investigation of Bismuthene in many different fields. Stable free-standing two-dimensional Bi monolayer (Bismuthene) structures have been predicted theoretically, but never realized experimentally. Here, the authors show a large-scale synthesis of free-standing Bismuthene and its electrocatalytic activity for CO2 reduction to formate. [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical reduction reaction of carbon dioxide (CO2RR) to carbon monoxide (CO) is the basis for the further synthesis of more complex carbon‐based fuels or attractive feedstock. Single‐atom catalysts have unique electronic and geometric structures with respect to their bulk counterparts, thus exhibiting unexpected catalytic activities. A nitrogen‐anchored Zn single‐atom catalyst is presented for CO formation from CO2RR with high catalytic activity (onset overpotential down to 24 mV), high selectivity (Faradaic efficiency for CO (FECO) up to 95 % at −0.43 V), remarkable durability (>75 h without decay of FECO), and large turnover frequency (TOF, up to 9969 h−1). Further experimental and DFT results indicate that the four‐nitrogen‐anchored Zn single atom (Zn‐N4) is the main active site for CO2RR with low free energy barrier for the formation of *COOH as the rate‐limiting step. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrathin BiNS decorated with monodispersed Pd NPs by two-step reconstruction was synthesized. • Near-unity formate selectivity over a broadscope low-potential window. • Breaking the limitation that Pd-site is easily poisoned by the generated CO at low overpotentials. • The capability of Pd-Bi interface for stabilizing and adsorbing *OCHO intermediate was revealed. • A new CO 2 RR mechanism with HCO 3 − participating as pre-proton donor for formate generation. 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. [ABSTRACT FROM AUTHOR]