Decoupled Control of CO2 and Nitrate Reduction Intermediates to Enable Efficient Tandem Urea Electrosynthesis

The direct electrochemical coupling of CO2 and nitrate (NO3-) offers a sustainable alternative to the energy-intensive Bosch-Meiser process for urea synthesis. However, achieving efficient C-N coupling at single active sites remains challenging due to the kinetic mismatch between CO2 and NO3- reduction, as well as the intricate multistep proton-coupled electron transfer process. Here, we present a sacrificial template-based strategy to synthesize a two-dimensional (2D)/zero-dimensional (0D) FeP0.9S2.9-x/Ag2S heterostructure catalyst, enabling the tandem coreduction of CO2 and nitrate for urea electrosynthesis. Electrochemical studies, in situ measurements, and theoretical calculations together demonstrate that the heterostructures with strongly coupled interfaces not only modulate the electronic structure but also enable decoupled control over NO3- and CO2 reduction. FeP0.9S2.9-x offers a moderate conversion rate from NO3- to ammonia, generating *NH2 intermediates while mitigating overhydrogenation to ammonia. Meanwhile, Ag2S with optimized loading facilitates efficient conversion of CO2 to CO, enabling the diffusion and electrophilic attack of CO on *NH2, thereby forming the critical *CONH2 intermediate for urea production. As a result, the FeP0.9S2.9-x/Ag2S tandem catalyst achieves a high urea yield rate of 1160.9 μg h-1 mgcat-1 with a Faradaic efficiency (FE) of 15.4% at -0.7 vs reversible hydrogen electrode, outperforming the individual FeP0.9S2.9 nanosheets and Ag2S nanoparticles. This study provides key insights into the rational design of heterostructure catalysts that exhibit strong interfacial interactions and allow for decoupled control over parallel reactions to enhance complex coupling processes.