Manipulating dehydrogenation kinetics through dual-doping Co3N electrode enables highly efficient hydrazine oxidation assisting self-powered H2 production

Abstract

Replacing sluggish oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) to produce hydrogen has been considered as a more energy-efficient strategy than water splitting. However, the relatively high cell voltage in two-electrode system and the required external electric power hinder its scalable applications, especially in mobile devices. Herein, we report a bifunctional P, W co-doped Co 3 N nanowire array electrode with remarkable catalytic activity towards both HzOR (−55 mV at 10 mA cm −2) and hydrogen evolution reaction (HER, −41 mV at 10 mA cm −2). Inspiringly, a record low cell voltage of 28 mV is required to achieve 10 mA cm −2 in two-electrode system. DFT calculations decipher that the doping optimized H* adsorption/desorption and dehydrogenation kinetics could be the underlying mechanism. Importantly, a self-powered H 2 production system by integrating a direct hydrazine fuel cell with a hydrazine splitting electrolyzer can achieve a decent rate of 1.25 mmol h −1 at room temperature.

Fabrication of a porous NiFeP/Ni electrode for highly efficient hydrazine oxidation boosted H2 evolution

“…), hydrazine oxidation reaction (H z OR) possesses ultra-low theoretical overpotential, single product, and safe environmental protection. Recently, substantial efforts have aimed at efficiently reducing electrolytic voltage via coupling H z OR with HER, 19,20 while it is still an urgent problem to seek low-cost, plentiful, active, and durable H z OR catalysts.…”

Stable and Highly Efficient Hydrogen Evolution from Seawater Enabled by an Unsaturated Nickel Surface Nitride

“…[46] The HzOR has a low equilibrium potential of −0.33 V versus RHE which can significantly reduce the overall cell voltage. [27,47] Furthermore, the by-product of the HzOR is inert N 2 which simplifies the electrolyzer operation. [48,49] For the HzOR, Ni-SN@C achieved a η 10 of only 16.8 mV, which was much lower than that for Pt/C and comparable to other catalysts ( Figure S18a, Supporting Information).…”

Recent Advances in Transition Metal Carbide Electrocatalysts for Oxygen Evolution Reaction

“…Note that in the above reactions, chemical groups such as O, OH, and OOH, are absorbed on the active sites (*) of catalysts, including physical or chemical absorption with no radicals involved as many literatures reported [31][32][33][34][35][36]. Generally, the formation of intermediates O* (Equation 15) and OOH* (Equation (16)) has been considered as RDS for OER, and previous literature has reported that TMCs are of great value to decrease overpotential for OER as it usefully accelerates RDS in kinetic process [32].…”

“…Their study revealed that Ni-Ni 3 C exhibited smaller Gibbs free energy change (1.815 eV) for the RDS than Ni (3.877 eV) and Ni 3 C (3.701 eV), indicating the important role of Ni 3 C, which efficiently accelerating kinetic process, thus deceasing the overpotential. Note that in different conditions, carbon atoms play diverse roles but similarly contributing to enhancing OER performance [35]. In the mechanism research, DFT calculation is essential, but the drawback of which is also clear.…”