Synergistic Integration of Amorphous Cobalt Phosphide with a Conductive Channel for Highly Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate reduction to ammonia (NORR) is regarded as a viable alternative reaction to "Haber Bosch" process. Nevertheless, it remains a major challenge to explore economical and efficient electrocatalysts that deliver high NH yield rates and Faraday efficiencies (FE). Here, it demonstrates the fabrication of a 3D core-shell structured Co-carbon nanofibers (CNF)/ZIF-CoP for NORR application. Benefitting from the distinct electron transport property of Co-CNF and desirable mass transfer ability from amorphous CoP framework, the as-prepared Co-CNF/ZIF-CoP exhibits large NH FE (96.8 ± 3.4% at -0.1 V vs reversible hydrogen electrode (RHE)) and high yield rate (38.44 ± 0.65 mg cm h at -0.6 V vs RHE), which are better than Co-CNF/ZIF-crystal CoP. Density functional theory (DFT) calculations further reveal that amorphous CoP presents a lower energy barrier in the rate determination step of the protonation of *NO to produce *NOH intermediates compared with crystal CoP, resulting in a superior NORR performance. Eventually, an aqueous galvanic Zn-NO battery is assembled by using Co-CNF/ZIF-CoP as cathode material to achieve efficient production of NH whilst simultaneously supplying electrical power. This work offers a reliable strategy to construct amorphous metal phosphide framework on conducting CNF as efficient electrocatalyst and enriches its promising application for NORR.