Mechanistic Insights and Catalytic Performance of Transition-Metal-Decorated PtS2 Catalysts for Electrocatalytic Reduction of Nitrate.

Abstract

Electrocatalytic reduction of hazardous water-pollutant nitrate offers an efficient and green approach for ammonia (NH3) generation, which is a sustainable alternative of Haber-Bosch process. However, the absence of a mechanistic understanding of the extremely complicated nitrate reduction reaction (NO3RR) and NH3 selectivity makes it difficult to discover reliable catalysts. We performed first-principles calculations to comprehensively examine the activity and selectivity of a single-atom catalyst (SAC) based on PtS2 for NO3RR. Based on the stability of catalysts, the adsorption energy of key intermediates, and the inhibition of the hydrogen evolution reaction (HER), two efficient systems, Ni/PtS2 and Cu/PtS2, with low value of limiting potentials (-0.18 and -0.21 V, respectively), were selected as promising candidates of electrocatalysts for NO3RR. Mechanistic analysis shows that the N-end pathway is most suitable with minimum energy barrier for ammonia generation. The partial density of state and charge transfer study confirm the effective activation of nitrate on the catalysts. Furthermore, ab initio molecular dynamics simulations were conducted to check the thermal stability of Ni/PtS2 and Cu/PtS2. Our findings reveal the design principle for more effective catalysts for NO3RR under ambient circumstances and present efficient catalysts for the generation of ammonia from nitrate.