Chalcogenide Vacancy Engineering on Tungsten Dichalcogenides for Selective Ammonia Synthesis via Electrocatalytic Nitrate Reduction Reaction

Because of readily tunable characteristics, two-dimensional transition metal dichalcogenides (2D TMDCs) can offer a wide variety of modifications for electrocatalytic applications. In this regard, computational studies guided by catalytically active-site engineering can deliver optimal electrocatalytic performance. Herein, chalcogenide vacancies (sulfur and selenium vacancies) on tungsten dichalcogenides (WS2 and WSe2) are probed as an active site for the theoretical evaluation (DFT calculations) of the electrocatalytic nitrate reduction reaction, and the findings are subjected to experimental verification. The sulfur vacancy containing exfoliated tungsten sulfide (ex-WS2) demonstrated the maximum ammonia production at −0.55 V vs Ag/AgCl with a Faradaic efficiency of 71.8%, whereas the selenium vacancy containing exfoliated tungsten selenide (ex-WSe2) achieved a maximum Faradaic efficiency of 95.6% at −0.5 V vs Ag/AgCl.