Superhydrophilic Ni‐based Multicomponent Nanorod‐Confined‐Nanoflake Array Electrode Achieves Waste‐Battery‐Driven Hydrogen Evolution and Hydrazine Oxidation

Abstract

The low thermodynamic potential (−0.33 V) and safe by‐product of N2/H2O, make utilizing hydrazine oxidation reaction (HzOR) to replace thermodynamically‐unfavorable and kinetically‐sluggish oxygen evolution reaction a promising tactic for energy‐efficient hydrogen production. However, the complexity of bifunctionality increases difficulties for effective material design, thus hindering the large‐scale hydrogen generation. Herein, we present the rationally designed synthesis of superhydrophilic Ni‐based multicomponent arrays (Ni NCNAs) composed of 1D nanorod‐confined‐nanoflakes (2D), which only needs −26 mV of working potential and 47 mV of overpotential to reach 10 mA cm−2 for HzOR and HER, respectively. Impressively, this Ni NCNA electrode exhibits the top‐level bifunctional activity for overall hydrazine splitting (OHzS) with an ultralow voltage of 23 mV at 10 mA cm−2 and a record‐high current density of 892 mA cm−2 at just 0.485 V, also achieves the high‐speed hydrogen yield driven by a waste AAA battery for OHzS.

Elucidating the Critical Role of Ruthenium Single Atom Sites in Water Dissociation and Dehydrogenation Behaviors for Robust Hydrazine Oxidation‐Boosted Alkaline Hydrogen Evolution

“…Supporting Information), indicating the significantly improved HzOR activity by doping Ru SAs in WS 2 , which implies the important role that Ru atoms take in the HzOR and Ru sites may be the main active centers for HzOR (Figure 5b). The attractive working potential of HzOR for CC@WS 2 /Ru-450 outperforms the other recently reported counterpart catalysts such as Mo-Ni 3 N/Ni/NF (−0.3 mV) [2] and Ni NCNAs (−26 mV) [57] (Figure 5g), etc. The detailed working potentials for each catalyst are provided in Table S3 of the Supporting Information.…”

Dual-strategy of hetero-engineering and cation doping to boost energy-saving hydrogen production via hydrazine-assisted seawater electrolysis

“…Furthermore, electrocatalytic HzOR provides a possible pathway for removing hydrazine from industrial sewage, which is expected to bring significant benefits in not only industrial sewage degradation but also energy-saving hydrogen production. Based on the foregoing, Li et al [16] built three-dimensional (3D) hierarchical arrays (Ni NCNA) onto nickel foam for hydrazine oxidation-assisted hydrogen evolution, achieving a much lower voltage of only 0.124 V to afford 100 mA cm −2 in the assembled two-electrode system, which is 1.583 V lower than that of the corresponding overall water splitting (OWS) system. Despite these exciting breakthroughs in pure alkaline water, some unprecedented challenges in the alkaline seawater system remain to be solved.…”

Constructing a bifunctional MoO2/Co heterojunction for efficient electrocatalytic hydrogen evolution and hydrazine oxidation

“…Recently, it has been demonstrated that the oxidation of thermodynamically favorable organic small molecules, such as urea, 25–27 hydrazine, 28–30 ethanol, 31,32 and 5-hydroxymethylfurfural, 33,34 instead of the oxygen evolution reaction, can effectively improve the anode reaction efficiency and achieve hydrogen production at a lower voltage. Among them, the hydrazine oxidation reaction (HzOR) has gotten a lot of attention because of its low theoretical oxidation potential (−0.33 V vs. RHE), safe and pollution-free byproduct (N 2 H 4 + 4OH − → N 2 + 4H 2 O + 4e − ), and adaptiveness to a separator free electrolyzer.…”