Reduced Mesoporous Co₃O₄ Nanowires as Efficient Water Oxidation Electrocatalysts and Supercapacitor Electrodes

Abstract

While electrochemical water splitting is one of the most promising methods to store light/electrical energy in chemical bonds, a key challenge remains in the realization of an efficient oxygen evolution reaction catalyst with large surface area, good electrical conductivity, high catalytic properties, and low fabrication cost. Here, a facile solution reduction method is demonstrated for mesoporous Co3O4 nanowires treated with NaBH4. The high‐surface‐area mesopore feature leads to efficient surface reduction in solution at room temperature, which allows for retention of the nanowire morphology and 1D charge transport behavior, while at the same time substantially increasing the oxygen vacancies on the nanowire surface. Compared to pristine Co3O4 nanowires, the reduced Co3O4 nanowires exhibit a much larger current of 13.1 mA cm‐2 at 1.65 V vs reversible hydrogen electrode (RHE) and a much lower onset potential of 1.52 V vs RHE. Electrochemical supercapacitors based on the reduced Co3O4 nanowires also show a much improved capacitance of 978 F g‐1 and reduced charge transfer resistance. Density‐functional theory calculations reveal that the existence of oxygen vacancies leads to the formation of new gap states in which the electrons previously associated with the Co‐O bonds tend to be delocalized, resulting in the much higher electrical conductivity and electrocatalytic activity.

A highly-efficient oxygen evolution electrode based on defective nickel-iron layered double hydroxide

“…2d). Besides, the band gap energy of R-NiFe LDH structure turned out to be 2.05 eV, which was smaller than that of P-NiFe LDH (2.81 eV), suggesting a better electro-conductivity of R-NiFe LDH [46,47]. Thus, our theory and experiment came to a good agreement, suggesting that by introducing oxygen vacancy defects in NiFe LDH electrode, the electronic structures on the catalysts' surface were finely tuned and the electrical conductivity was improved, finally leading to the significantly enhanced OER activity.…”

A facile synthesis of reduced Co3O4 nanoparticles with enhanced Electrocatalytic activity for oxygen evolution

“…Owing to the weak CoeO bond and low hopping barriers [29,30], Co 3 O 4 has been regarded as an ideal catalyst by NaBH 4 reduction to realize the increasing of oxygen vacancies. For instance, Wang et al have found that after reacting with NaBH 4 solution, the catalytic activity of Co 3 O 4 for OER can be dramatically enhanced [19]. Based on the above consideration, here we reported a facile method to prepare uniformly reduced Co 3 O 4 nanoparticles with high surface area and more oxygen vacancies.…”

“…More importantly, tuning nanostructures or doping of Co 3 O 4 may provide more surface oxygen vacancies, which has great effective on improving the activity for OER [18,25,26]. Recently, two kinds of method for improving oxygen vacancies of the surface oxides have been investigated including the annealing in H 2 atmosphere [27] and direct reduction treatment by NaBH 4 [19,28]. Owing to the weak CoeO bond and low hopping barriers [29,30], Co 3 O 4 has been regarded as an ideal catalyst by NaBH 4 reduction to realize the increasing of oxygen vacancies.…”

Impedimetric sensing of humidity and temperature using CeO2–Co3O4 nanoparticles in polymer hosts

“…Keeping in view the importance of doping and nanocomposition we have selected CeO 2 -Co 3 O 4 nanoparticles because both are low cost and earth abundant materials [18,19]. Co 3 O 4 nanomaterials have shown much application in different sectors.…”