The surface engineering of MOF-derived titanium oxide–carbon multifunctional composite catalyst for efficient electrochemical nitrogen reduction

Abstract Electrochemical nitrogen reduction reaction (eNRR) is a promising strategy for ammonia (NH3) synthesis owing to its features of sustainability and non-pollution. However, the nonpolar N2 triple bond (N N) and competitive hydrogen evolution reaction (HER) cause eNRR to be far away from practical applications. Hence, the multifunctional composite catalysts are designed to overcome the extreme conditions by the combinaton of surface engineering and structural design. Benefiting from the oxygen vacancy (OV), phase heterogeneous interface and functional porous carbon matrix, OV-TiO2@C/Cu possesses superior eNRR performance that NH3 yield and Faradaic efficiency achieve 16.10 μg h−1 mg−1 at −0.60 V vs. RHE and 6.04% at −0.55 V vs. RHE, respectively. On the basis of the in-situ Raman spectra analysis, the characteristic peaks of O Ti O symmetric stretching vibration and phase heterogeneous structure gradually become weak under the various potentials electrolysis, which indicates that OV and heterogeneous interface can serve as electron trappers and active sites to absorb N2. The rational combination of surface engineering and composite structure design for creating active sites will open new avenues beyond the use of noble metal-based catalysts for eNRR.