CoP nanowires on carbon cloth for electrocatalytic NOx− reduction to ammonia

Abstract

• Cobalt Phosphide (CoP) with uniform nanowire array morphology self-supported on carbon cloth (CC) was prepared and used as cathode. • The material demonstrated effective electrocatalytic activity for NO x − (NO 2 – and NO 3 – ) reduction in alkaline solution at low overpotentials. • The catalyst maintained robust electrocatalytic activity even after 10 repeated tests. Electrocatalysis provides a promising green solution to replace the industrial Haber-Bosch process for ammonia production under ambient conditions. The indirect method for ammonia synthesis (N 2 → NO x → NH 3 ) have recently received great attention and development of efficient catalysts for selective NO x conversion to NH 3 is of key importance. Herein, we report the preparation of uniform CoP nanwire arrays self-supported on carbon cloth as efficient catalyst for electrocatalytic nitrite (NO 2 – ) and nitrate (NO 3 – ) reduction to synthesize ammonia in alkaline NaOH solution. The material demonstrated efficient ammonia generation rate of 380 µg*h −1 *cm −2 for NO 2 – reduction and a faradic efficiency of 91.6% obtained at −0.3 V vs RHE, and 317 µg*h −1 *cm −2 for NO 3 – reduction and a faradic efficiency of 65% at −0.4 V vs RHE. More importantly, the CoP catalyst displayed robust stability and maintained its activity even after 10 cycles of elctrocatalysis. This work demonstrated the great potential of carbon cloth supported metal phosphides for efficient ammonia production through electrocatalytic NO x conversion.