Face-Dependent Reconstruction of Bi-Oxyiodides toward Selective Growth of (BiO)2CO3 Edge Side to Maximize CO2 Conversion Efficiency.

Chemical reconstruction of bismuth oxyiodides using bicarbonates is tried to selectively grow (BiO)2CO3 edge side. Orthorhombic o-Bi5O7I undergoes a total reconstruction process by its phase transformation into tetragonal (BiO)2CO3 (BOC-o) to form a well-aligned nanosheet array with maximally exposing CO32- moiety at the edge side. The post-reconstruction BOC-o catalyst achieved 100% Faradaic efficiency at -0.86 V vs. RHE for CO2-to-formate conversion. However, another conservative reconstruction of tetragonal t-BiOI into tetragonal (BiO)2CO3 (BOC-t) exposed majorly a less reactive [BiO]+ layer. At low overpotential regions, the catalytic cycle of BOC-o begins with the initial conversion of the CO32- moiety into formate at the [-OBi-(CO3)-BiO-] site, but at high overpotential regions, the [BiO]+ layer undergoes reduction to metallic Bi and multi-catalytic species proceed with CO2 reduction. Otherwise, the deactivation of Bi+ site by an organic molecule switched on another catalysis of proton reduction, preventing CO2 reduction.