Vanadium-Doping and Interface Engineering for Synergistically Enhanced Electrochemical Overall Water Splitting and Urea Electrolysis

Abstract

Fabricating effective non-precious metal-based catalysts for hydrogen production via electrochemical water splitting is of considerable importance but remains challenging. Transition metal nitrides possessing metallic character and corrosion resistance have been considered as potential replacements for precious metals. However, their activities for water electrolysis are impeded by the strong hydrogen adsorption and low water adsorption energies. Herein, V-doped bimetallic nitrides, V-FeNi3N/Ni3N heterostructure, are synthesized via a hydrothermal–nitridation protocol and used as electrocatalysts for water splitting and urea electrolysis. The V-FeNi3N/Ni3N electrode exhibits superior HER and OER activities, and the overpotentials are 62 and 230 mV to acquire a current density of 10 mA cm–2, respectively. Moreover, as a bifunctional electrocatalyst for overall water splitting, a two-electrode device needs a voltage of 1.54 V to reach a current density of 10 mA cm–2. The continuous electrolysis can be run for more than 120 h, surpassing most previously reported electrocatalysts. The excellent performance for water electrolysis is dominantly due to V-doping and interface engineering, which could enhance water adsorption and regulate the adsorption/desorption of intermediates species, thereby accelerating HER and OER kinetic processes. Besides, a urea-assisted two-electrode electrolyzer for electrolytic hydrogen production requires a cell voltage of 1.46 V at 10 mA cm–2, which is 80 mV lower than that of traditional water electrolysis.

Vanadium-Doped Nickel Cobalt Layered Double Hydroxide: A High-Performance Oxygen Evolution Reaction Electrocatalyst in Alkaline Medium

“…Recently, doping of vanadium ions not only in LDH lattices but also in several transition-metal-based electrocatalysts would result in improvisation of OER kinetics. , Wang et al reported that the doping of Ni 3 S 2 for OER and doping of V 3+ ions result in a decrease in overpotential values by 241 mV . On the other hand, in another report, Sun et al reported the formation of V-doped FeNi 3 N/Ni 3 N heterostructure materials for OER and urea oxidation. − The V-doped FeNi 3 N/Ni 3 N demands an overpotential value of 230 mV, whereas FeNi 3 N/Ni 3 N demands 244 mV, and the improvisation of OER kinetics arise owing to electronic modification at the interface of the two-nitride entity as a result of V doping. He et al .…”

Metal–Organic Framework-Based Self-Supporting Nanoparticle Arrays for Catalytic Water Splitting

“…Corresponding to the HER test, the OER performance of the obtained catalyst was also analyzed using a three-electrode system. As shown in Figure a, ZIF-67/NiCo-S/NF as the OER catalyst had an outstanding performance compared with NiCo-LDH/NF, ZIF-67/NiCo-LDH/NF, and NF. − Only overpotentials of 127, 201, and 255 mV were required to reach current densities of 10, 50, and 100 mA cm –2 . Surprisingly, ZIF-67/NiCo-S/NF required only an overpotential of 358 mV to reach a large current density of 500 mA cm –2 .…”

Circumventing Challenges: Design of Anodic Electrocatalysts for Hybrid Water Electrolysis Systems

“…Favorable adsorption and desorption energies of reactants and products were thus optimized for higher HER and UOR electrocatalytic activities (Figure 14m-o). Additionally, other works of Ru-doping in Ru-Co 2 P/N-C/NF [151] and NiFeRu-LDH, [152] V-doping in Fe, V-NiS/NF, [153] V-FeNi 3 N/Ni 3 N, [154] NiMoV LDH/NF [155] and V-Ni 3 N/NF, [156] Fe-doping in CoNiFeS-OH, [157] P doping in F-P-Co 3 O 4 , [158] F-doping in F-Ni(OH) 2 [159] were also recently reported, inducing electrocatalytic UOR activity enhancement in different catalyst systems.…”