Breaking Structural Instability and Orbital Symmetry Mismatch in <i>p</i>-Block Metal Monochalcogenides for CO<sub>2</sub> Electroreduction via Noninvasive van der Waals Doping
Pengfei Li, Xu Han, Fangqi Yang, Ning Li, Meng-Xuan Li, Jing Li, Xiaoxu Zhao, Meng Zhao, Zejun Li, Wenping Hu, Jiong Lu
Abstract
P -block metal monochalcogenides (MX) adopting black phosphorus (BP)-like structures are promising electrocatalysts due to their abundant exposed metal sites and tunable electronic structures. However, their practical application is limited by structural instability arising from lone-pair electron-induced structural distortions, along with an inherent orbital symmetry mismatch with the frontier orbitals of small molecules (e.g., CO 2 ), reducing the activation efficiency. Here, we report a noninvasive doping strategy to overcome both structural instability and orbital symmetry mismatch in p -block metal monochalcogenides for efficient CO 2 electroreduction, through engineering a periodic van der Waals (vdW) superlattice, known as a misfit superlattice. These vdW superlattices with tunable sublayer ratios contain the catalytically active p -electron-rich MX sublayers and conductive transition metal dichalcogenide current collectors. Taking [BiS] 1 [TaS 2 ] 1 as a proof-of-concept, the presence of noninvasive vdW doping and ionic interactions between sublayers is crucial for modulating their electronic structures and stabilizing BiS sublayers by transforming the Bi into a higher valence state of Bi (2+δ) . Concurrently, interlayer noninvasive vdW doping induces uneven electron redistribution in Bi’s p -orbitals, breaking its orbital symmetry mismatch with the LUMO of CO 2, thereby reducing the CO 2 activation barrier. In situ characterization and theoretical calculations reveal that the optimized Bi sites exhibit moderate adsorption for the *OCHO, endowing the superlattice with exceptional selectivity (>90%) for formate in CO 2 electroreduction. This work advances vdW superlattice engineering as a versatile platform for synergistically stabilizing layered p -block materials and tailoring their sublayer interactions and orbital symmetry alignment by leveraging noninvasive vdW doping, achieving optimal catalytic performance for the efficient electrochemical conversion of small molecules.