Efficient electrochemical reduction of nitrate by bimetallic Cu-Fe phosphide derived from Prussian blue analogue

Designing electrocatalysts for nitrate (NO3-) reduction with excellent activity, low cost and stability is of great interest. Herein we synthesized a novel transition bimetallic phosphide (CuFeP-x, x referred to the phosphidation temperature) catalyst by phosphidation using CuFe-Prussian blue analogue (PBA) nanoparticles as the precursor. The obtained CuFeP-450 maintained the morphology of nanocube with the average size of 33.0 nm and bimetallic phosphide nanoparticles formed during the phosphidation process. The higher electrocatalytic activity of CuFeP-x in electrochemical NO3- reduction were attained as compared to that of calcined CuFe-450, because the CuFeP-x have a lower interface impedance and the dominated species for NO3- reduction changes from electron to atomic H* , which effectively enhanced the removal rate. The appropriate phosphidation temperature can form a crystal structure that facilitated reaction kinetics. As a result, CuFeP-450 showed the best electrocatalytic performance for NO3- reduction (99.42%), and the selectivity of N2 can reach nearly 100% under the condition of 1000 mg L−1 chloride ions. This simple method using PBA with binary transition metals to prepare bimetallic phosphide provides a new direction for designing efficient non-noble metal electrocatalysts for NO3- reduction.