Breaking Structural Instability and Orbital Symmetry Mismatch in p-Block Metal Monochalcogenides for CO₂...

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., CO₂), 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 CO₂ 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[TaS₂]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 CO₂, thereby reducing the CO₂ 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 CO₂ 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.