Anion–Cation Double Doped Co₃O₄ Microtube Architecture to Promote High-Valence Co Species Formation for Enhanced Oxygen Evolution Reaction

Abstract

A method for efficiently catalyzing the oxygen evolution reaction (OER) represents a top priority for water electrolysis due to its multistep electron transfer pathway and sluggish kinetics. The OER activity can be promoted by generating high valence transition-metal species in the electrocatalysts. In the present work, a versatile anion–cation double doped Co3O4 (Se/Ni-Co3O4) microtube architecture is innovatively fabricated as an OER electrocatalyst, by combining reliable and template-free solvothermal strategy and calcination treatment. The obtained Se/Ni-Co3O4 possesses some desirable properties for OER including an attractive mesoporous structure, abundant exposed active species associated with surface oxygen vacancies, and fast charge transfer rate. By precisely exploring the redox reaction behavior, it is found that the effective Se and Ni double doping could readily promote the generation of active Co­(IV) species. Consequently, the obtained Se/Ni-Co3O4 electrocatalyst affords a very good OER electrocatalytic activity with an onset potential of 1.47 V, small Tafel slope (62.9 mV dec–1), and excellent durability in alkaline solution, which is even superior to that obtained in the benchmark RuO2. The novel strategy introduced in this research may open a new opportunity for the rational design of highly efficient Co3O4-based OER electrocatalysts.

Constructed Interfacial Oxygen‐Bridge Chemical Bonding in Core‐Shell Transition Metal Phosphides/Carbon Hybrid Boosting Oxygen Evolution Reaction

“…Usually, phosphating processes take place at 350°C. [51] It can be inferred that phosphating at 300°C and the carbon layer showed a poor degree of crystallinity, which were beneficial for the formation of the CoÀ OÀ C bond. Co 3 O 4 /rGO transformed to CoP/rGO at 300°C, but there were no CoÀ OÀ C bonds.…”

“…[50] In general, in alkaline solution, the OER mechanism undergoes a multipleelectron transfer for converting OH À to O 2 , which can be described as follows [Eqs. (1)-( 4)]: [51] *…”

“…To further understand the effects of phosphating processes on the structure and coordination, thermogravimetric (TGA) and derivative thermogravimetric analysis (DTGA) were performed to confirm the change process of Fe 2 O 3 @PDA@Co 5 (OH) 9 NO 3 intermediate during the annealing process in the tube furnace under N 2 protection without the existence of NaH 2 PO 2 : the intermediate started to lose weight at 200 °C, and after 400 °C there was nearly no weight lost, implying the precursor transformed completely (Figure S9). Usually, phosphating processes take place at 350 °C [51] . It can be inferred that phosphating at 300 °C and the carbon layer showed a poor degree of crystallinity, which were beneficial for the formation of the Co−O−C bond.…”

“…In general, in alkaline solution, the OER mechanism undergoes a multiple‐electron transfer for converting OH − to O 2 , which can be described as follows [Eqs. (1)–]: [51] …”

New TiO2‐Based Oxide for Catalyzing Alkaline Hydrogen Evolution Reaction with Noble Metal‐Like Performance

“…Hydrogen has been considered as an ideal and sustainable energy for the future due to its carbon‐free nature and the highest gravimetric energy density. [ 1–5 ] Alkaline water electrolysis is one of the most promising ways for hydrogen production which generated by cathodic hydrogen evolution reaction (HER). [ 6–10 ] To achieve high efficiency of hydrogen production, efficient electrocatalysts are urgently demanded to accelerate HER kinetics.…”