Monolithic Ni‐Mo‐B Bifunctional Electrode for Large Current Water Splitting

Abstract

Screening and developing highly efficient electrodes is key to large-scale water electrolysis. The practical industrial electrode should fulfill several criteria of high activity, structural stability, and fast bubble evolution at a large current density. In this study, a novel monolithic 3D hollow foam electrode that can achieve the requirements of large current density water electrolysis is developed and fabricated through a simple electroless plating-calcination strategy. This strong 3D Ni-Mo-B hollow foam electrode can withstand a pressure of 2.37 MPa and exhibits high electrochemical surface area, high conductivity, and low gas transfer resistance, drastically boosting its catalytic performance. It affords 50 mA cm -2 at overpotentials of only 68 mV for hydrogen evolution reaction and 293 mV for oxygen evolution reaction and can survive at a large current density of 5 A cm -2 while maintaining its structure and performance in 1.0 m KOH. The advantages of facile preparation, high mechanical strength, high gas mass transfer ability, and excellent performance enable this structure to be a potential electrode, active substrate, or 3D catalyst in many fields.

Underfocus Laser Induced Ni Nanoparticles Embedded Metallic MoN Microrods as Patterned Electrode for Efficient Overall Water Splitting

“…[44] The characteristic peaks of NiOOH appeared in the FT-IR spectrum (Figure S17, Supporting Information), which confirmed the formation of NiOOH. [43] Due to excellent performance of Ni/MoN/rNS for HER and OER in 1 m KOH, the Ni/MoN/rNS was integrated as both anode and cathode to construct water-alkali electrolyzer for overall water splitting (Figure 6e). To deliver a current density of 300 mA cm −2 , Ni/MoN/rNS||Ni/MoN/rNS merely required 2.4 V in 1 m KOH, which was a little bit lower than that of (−) 20 wt% Pt/C/rNS||RuO 2 /rNS (+).…”

“…[ 42 ] After OER process, the defined band at 554 cm −1 appeared that belong to thin layer NiOOH on NiMoN/rNS. [ 43 ] Furthermore, the new peak at 900 cm −1 was assigned to MoO 4 2− in alkaline solution, which originated from dissolution of Mo species. [ 44 ] The characteristic peaks of NiOOH appeared in the FT‐IR spectrum (Figure S17 , Supporting Information), which confirmed the formation of NiOOH.…”

“…[ 44 ] The characteristic peaks of NiOOH appeared in the FT‐IR spectrum (Figure S17 , Supporting Information), which confirmed the formation of NiOOH. [ 43 ]…”

Recent progress on the long‐term stability of hydrogen evolution reaction electrocatalysts

“…For example, Liu et al prepared monolithic Ni‐Mo‐B HF catalysts that can sustain the water electrolysis at high current densities of 450 mA cm −2 for 300 h (Figure 15A) and even at ultra‐high current densities of 1, 2, and 5 A cm −2 for 170, 54, and 20 h each in alkaline electrolytes (insets of Figure 15A). 195 The optical photo of H 2 bubbles attached to Ni‐Mo‐B HF revealed that their H 2 bubble diameters were much smaller than those on pure NF. The small stretching force generated by the small bubbles will minimize the damage to the electrode and thus prolong the life of the electrode (Figure 15B,C).…”

“…WS 2 MSLs 0.5 M H 2 SO 4 60 200@20@--- [190] Cu 2 O x S 1Àx /Cu 1 M KOH 40 113@12@--1000@- [191] FeP x /Fe-N-C/NPC 0.5 M H 2 SO 4 / 1 M KOH 75/182 --2000@-/- [192] FeP/Ti 0.5 M H 2 SO 4 /1 M KOH 79/95 -@10@-/-@10@--- [193] N-NiCo 2 S 4 1 M KOH 41 50@1000@68.2% -- [194] Ni-Mo-B HF 1 M KOH 68@50 1.8 V@300@-(OWS) -500@- [195] MoO x /Ni 3 S 2 /NF 1 M KOH 106 110@200@--10 000@- [196] P-NiMoHZ 1 M KOH 23 -1000@200@-- [197] NiCo 2 O 4 /Cu x O/Cu 1 M KOH 92 -@150@--500@- [198] CN Ni2P/CoP-150 0.5 M H 2 SO 4 160 -10@120@-5000@- [199] WO 3 /C@CoO/NF 1 M KOH 55 -10@110@-2000@- [200] NiMo-EDA 1 M KOH 72 350@100@---…”