A Unique Amorphous Porous BiSbO_x Nanotube with Abundant Unsaturated Sb-Stabilized BiO_8-x Sites for Efficient CO₂ Electroreduction in a Wide Potential Window

The CO2 electroreduction reaction using sustainable electricity emerges as a viable strategy to produce high-value-added and profitable chemicals. The achievement of superior activity at a lower overpotential and higher selectivity in a wide potential window is vitally important for large-scale industrial applications. Herein, a carbon-composite amorphous porous BiSbOx nanotube with abundant unsaturated sites is reported to boost the conversion of CO2 to formate, exhibiting a formate selectivity of >90% in an extremely broad range of potentials from -0.5 to -1.4 V versus reversible hydrogen electrode (RHE) and a maximal energy conversion efficiency of 77.1%. Importantly, pure formic acid solution is directly obtained in a solid-electrolyte cell for industrial-scale applications. The porous tubular structure can expose more catalytic active sites, accelerate the mass transfer, and show fast surface charge transfer. Moreover, the unique coordination-unsaturated Sb-stabilized BiO8-x site can not only enhance the adsorption and activation of CO2 but also reasonably balance the stabilization and hydrogenation of *OCHO intermediate, thus leading to its obviously higher catalytic performance. As a result, a novel amorphous porous BiSbOx nanotube is successfully designed for efficient CO2 electroreduction, which may shed new light on developing many more amorphous composite metal oxide catalysts for conversion of inert small molecules.