Key Role of NiCoP Arrays as an Electron Reservoir in a Membrane-Free Electrochemical Reactor for Energy-Saving Hydrogen Recovery and Ammonia Decomposition

Abstract

In this study, we developed a membrane-free electrochemical reactor by directionally regulating the electron storage release of the NiCoP array electron reservoir, which realized high-efficiency removal of ammonia and simultaneous hydrogen purification. In the ammonia removal cell, indirect oxidation based on electrocatalytic chlorine evolution achieved effective removal of ammonia, while electrons were stored by the NiCoP array auxiliary electrode in the oxidation state at the cathode. In the hydrogen production cell, the electrons released from NiCoP arrays in the reduction state were obtained at the cathode to produce hydrogen with a purity of nearly 100% and a Faraday efficiency of 90.8%. The reactor maintained stable operation during 30 cycles of reversing the position of the two auxiliary electrodes, which was owing to the excellent circulating electron storage release ability of NiCoP arrays. Our proof-of-concept reactor provides a new development idea for energy recovery from wastewater.