The role of synthesis vis-à-vis the oxygen vacancies of Co3O4 in the oxygen evolution reaction†
Abstract
The oxygen evolution reaction over oxide vacancy-induced spinel Co3O4 is a topic of tremendous scientific attention owing to the favourable adsorption of water, as also shown here through DFT calculations. However, the inclusion of an optimum amount of oxygen-ion vacancies at the surface and in the bulk of Co3O4 remains a synthetic challenge in order to enhance the efficacy of the oxygen evolution reaction. Here, we have attempted a single-step scalable approach of solution combustion synthesis to incorporate the oxide ion vacancies in high-surface-area Co3O4. To benchmark the catalyst, we also synthesized Co3O4 using elevated-temperature calcination routes. Detailed structural and surface analyses revealed the significant presence of oxide ion vacancies in the combustion-synthesized material. The solution combustion synthesized Co3O4 due to the presence of oxygen-ion vacancies exhibited an excellent oxygen evolution reactivity with a lower overpotential and higher current density compared with the other Co3O4 materials synthesized using calcination routes. Tafel slope calculations indicated that the formation of surface hydroxyl species through water dissociation over the oxide ion vacancies is the rate-determining step of the overall reaction. The mechanistic role of the oxygen-ion vacancies in the oxygen evolution reaction was further explored via DFT studies.
Please wait while we load your content...
