Rational Construction of Indium-TiO₂ Interfacial Composites for Boosting Urea Electrosynthesis

The electrocatalytic co-reduction of CO₂ and nitrate to urea offers a sustainable route for carbon fixation, nitrogen waste recycling, and high-value chemical production. However, the rational design of efficient electrocatalysts with synergistic activation capability toward both reactants and the ability to suppress side reactions remains challenging. Herein, an N-doped carbon-modified In-TiO₂ interfacial composite catalyst (In-TiO₂/NC) was fabricated via a solvothermal method followed by high-temperature calcination. The catalyst exhibits a urea yield rate of 618.9 μg·h^-1·mg_cat.^-1 at -1.0 V vs. RHE. Control experiments verify that urea is generated through C-N coupling between intermediates derived from CO₂ reduction and nitrate reduction. Density functional theory calculations indicate that the coupled In and TiO₂ components strengthen CO₂ adsorption, maintain favorable nitrate activation, improve the electronic states available for charge transfer, and suppress the hydrogen evolution reaction. This work demonstrates that rational interfacial coupling of catalytic components can promote electrocatalytic urea synthesis from CO₂ and nitrate, providing a promising strategy for high-performance C-N coupling electrocatalysts.