Monoatomic alloys (SaaS) have shown great potential in various electrocatalytic reactions. However, the effect of the atomic orbital hybridization effect of SaaS on electrochemical reactions is not well understood. Based on this,Professor Zhang Jintao of Shandong University (corresponding author) and othersThe in-situ growth of vanadium (V), molybdenum (Mo) and tungsten (W) atoms on bismuth (Bi) nanosheets was reported, creating a SaaS with abundant grain boundaries. Through detailed microstructure and composition analysis, the strong P-D orbital hybridization between Bi and V makes it exhibit excellent electrocatalytic performance in carbon dioxide (CO2) reduction reactions.
In this paper, DFT calculations were used to study the correlation between the electronic properties and atomic modes of V-Bi, Mo-Bi and Bi(012) and their respective catalytic activities. The charge accumulation on the v (mo) atom illustrates the charge delocalization of v (mo) by the neighboring bi atoms, showing a significant electron transfer effect. CO2 will be activated by proton electron pair transfer or adsorption of *H intermediates, and *H can bond with the C and O atoms of CO2 to form *OCO and *COOH intermediates, respectively, and further form HCOOH and CO. The results show that the generation of *OCO is more favorable than the *COOH intermediate, and the rate-determining step (RDS) on V-Bi is the first proton-coupled electron transfer step, with an energy barrier of 056 ev。Therefore, thermodynamically favorable HCOOH conversion can be easily achieved on the V-Bi SAA catalyst with abundant grain boundaries.
The Fractional Density of States (PDOS) diagram shows that the transfer of electrons from Bi to V will result in electron-electron repulsion between charge-accumulating V atoms and electron-rich O atoms benefiting from P-D orbital hybridization. Conversely, with the depletion of electrons from O to Bi atoms by strong bonds, the synergistic coupling of the *OCH energy level with the Bi orbital is described, resulting in a strong interaction. Therefore, the anchoring of a single V atom on the BI substrate will lead to efficient regulation of the electronic structure, thereby accelerating the activation of CO2 and facilitating the subsequent proton-coupled electron transfer reactions, which are essential for formate generation.
strong p-d orbital hybridization on bismuth nanosheets for high performing co2 electroreduction. adv. mater.,, doi: 10.1002/adma.202309648.
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