Intermetallic PtTe metallene for formic acid oxidation assisted electrocatalytic nitrate reduction

Abstract

Development of highly efficient electrocatalysts for selective electroreduction of nitrate is of great significance. In this work, the ultrathin intermetallic platinum-tellurium metallene (PtTe-ML) with atomic thickness is synthesized by simple liquid-phase chemical reduction. The introduction of Te atoms can sharply weaken the catalytic activity of Pt for the hydrogen evolution reaction. And, PtTe-ML exhibits superior catalytic activity for the nitrate reduction reaction (NO3−-ERR) than Pt black. In 0.5 M H2SO4 solution, PtTe-ML achieves an effective ammonia (NH3) production rate of 2.32 mg h−1 mgcat−1 and a Faradic efficiency of 95.5% at −0.04 V potential for NO3−-ERR. Meanwhile, the entry of Te atom isolates the continuous Pt active site and increases the proportion of the direct dehydrogenation pathway of the formic acid oxidation reaction (FAOR). Therefore, PtTe-ML also exhibits excellent FAOR activity due to the optimization of FAOR pathway. Then, anodic FAOR with low anodic oxidation potential is used to replace the oxygen evolution reaction with slow kinetic, so that the total electrolytic voltage of conventional electrochemical NH3 production can be effectively reduced. Consequently, the bifunctional PtTe-ML electrocatalyst requires only 0.4 V total voltage for FAOR assisted NH3 electroproduction. This work demonstrates a reaction coupling strategy to significantly improve the utilization rate of electric energy in electrochemical synthesis.