Enhanced Charge Carrier Dynamics on Sb Se Photocathodes for Efficient Photoelectrochemical Nitrate Reduction to Ammonia.

Ammonia (NH ) is recognized as a transportable carrier for renewable energy fuels. Photoelectrochemical nitrate reduction reaction (PEC NO RR) offers a sustainable solution for nitrate-rich wastewater treatment by directly converting solar energy to ammonia. In this study, we demonstrate the highly selective PEC ammonia production from NO RR by constructing a CoCu/TiO /Sb Se photocathode. The constructed CoCu/TiO /Sb Se photocathode achieves an ammonia Faraday efficiency (FE) of 88.01 % at -0.2 V and an ammonia yield as high as 15.91 μmol h  cm at -0.3 V with an excellent onset potential of 0.43 V . Dynamics experiments and theoretical calculations have demonstrated that the CoCu/TiO /Sb Se photocathode possesses high light absorption capacity, excellent carrier transfer capability, and high charge separation and transfer efficiencies. The photocathode can effectively adsorb the reactant NO and intermediate, and the CoCu co-catalyst increases the maximum Gibbs free energy difference between NO RR and HER. Meanwhile, the Co species enhances the spin density of Cu, and increases the density of states near the Fermi level in pdos, which results in a high PEC NO RR activity on CoCu/TiO /Sb Se . This work provides a new avenue for the feasibility of efficient PEC ammonia synthesis from nitrate-rich wastewater.