Boosting electrochemical nitrogen reduction performance through water-in-salt electrolyte

Abstract

While electrochemical nitrogen reduction reaction (NRR) stands as a promising technique for sustainable NH3 fabrication due to its mild operation conditions, it has long been suffered from low efficiency and poor selectivity owing to the inertness of N2 and competition hydrogen evolution reaction (HER). Herein, we report the use of oxygen vacancy rich TiO2 loaded with Au nanoparticles as NRR catalyst in super concentrated lithium bis(trifluoromethane sulfonyl) imide (Li TFSI) “water-in-salt” system (20 M electrolyte) and obtain the Faradaic efficiency of 37.2 % with an NH3 yield rate of 20.3 μg h−1 cm−2 at − 0.4 V vs RHE, accompanied by the significant decay of both current density and onset potential of hydrogen evolution reaction. Electrochemical experimental and theoretical calculation results indicate that the HER process can be greatly hindered both kinetically and energetically. The unique effect of this “water-in-salt” electrolyte would offer a new idea to improve the NRR selectivity via HER suppression.