Selenium vacancies regulate d-band centers in Ni3Se4 toward paired electrolysis in anion-exchange membrane electrolyzers for upgrading N-containing compounds

Paired electrolysis in anion-exchange membrane (AEM) electrolyzers toward the cathodic nitrate reduction reaction (NO 3 RR) and anodic benzylamine oxidation reaction (BOR) could generate high value-added N-containing compounds simultaneously. The key challenge is to develop bifunctional electrocatalysts with a wide potential window, which can achieve highly efficient conversion of anode and cathode reactants. Herein, Ni 3 Se 4 with Se vacancies was prepared and employed as the cathode and anode of AEM electrolyzers for NO 3 RR and BOR. 15 N isotope-labeling online differential electrochemical mass spectrometry (DEMS) proved that ammonium was reduced from nitrates and revealed the reaction pathway of NO 3 RR. The density functional theory calculation clarified that Se vacancies regulate d-band centers, and then further modulate the adsorption energy of adsorbed hydrogen, NO 3 − and intermediates on the Ni 3 Se 4 -60s surface in NO 3 RR, so as to optimize the hydrogenation of NO 3 − into ammonia. Moreover, during the BOR, the Se vacancy can promote the adsorption of OH − , which is easier to form the active species of NiOOH. The technical and economic evaluation exhibited that the cost of paired electrolysis is 1.21 times lower and the profit is 1.42 times higher than that of the unpaired electrolysis, which shows the economic attraction of paired electrolysis. This work delivers the guidance for the design of efficient catalysts for paired electrolysis in AEM electrolyzer toward the sustainable synthesis of value-added chemicals.