Active Electron Density Modulation of Co₃O₄‐Based Catalysts Enhances their Oxygen Evolution Performance

Abstract

Despite the fact that many strategies have been developed to improve the efficiency of the oxygen evolution reaction (OER), the precise modulation of the surface electronic properties of catalysts to improve their catalytic activity is still challenging. Herein, we demonstrate that the surface active electron density of Co3O4 can be effectively regulated by an argon‐ion irradiation method. X‐ray photoelectron and synchrotron x‐ray absorption spectroscopy, UV photoelectron spectrometry, and DFT calculations show that the surface active electron density band center of Co3O4 has been upshifted, leading to a significantly enhanced absorption capability of the oxo group. The optimized Co3O4‐based catalysts exhibit an excellent overpotential of 260 mV at 10 mA cm−2 and Tafel slope of 54 mV dec−1, superior to the capability of the benchmark RuO2, representing one of the best Co‐based OER catalysts. This approach could guide the future rational design and discovery of ideal electrocatalysts.

Highly Efficient Alkaline Water Splitting with Ru‐Doped Co−V Layered Double Hydroxide Nanosheets as a Bifunctional Electrocatalyst

“…For improved OER performance, various strategies have been developed by strengthening the ΔG *O to accelerate the formation of *O [6] . Rich coordinatively unsaturated Co cations and/or oxygen vacancies are introduced by, for example, plasma, annealing, ion‐irradiation etc., to modulate the highest‐occupied d ‐state relative to the Fermi level of Co atoms, thus facilitating the bonding to O 2p for improved OER activity [6a,b,7] . Doping second metals (mainly Fe) in the Co hydroxide/oxide matrix is also highly efficient to boost the OER activity because the Fe cations in the di‐μ‐oxo‐bridged Co–Fe bond on the surface/defect/edge sites are able to generate and stabilize the oxygen radicals [8] .…”

Heterogenization of Ionic liquid Boosting Electrochemical Oxygen Reduction Performance of Co3O4 Supported on Graphene Oxide

“…Considering the strong 311 crystal plane of Co 3 O 4 in the XRD pattern, a calculation model was established based on it with Co as the active center, and then the ORR process was simulated on Co 3 O 4 /GO and Co 3 O 4 /ILÀ GO surfaces. [58][59] The free energy diagrams show that the intermediate species adsorbed on Co 3 O 4 /ILÀ GO is more stable than that on Co 3 O 4 / GO. Especially, the free energy of *OO and *OOH was calculated to be 3.31 eV and 2.77 eV for Co 3 O 4 /ILÀ GO, which is much smaller than 4.09 eV and 3.61 eV for Co 3 O 4 /GO (Figure 4a) .…”

“…In order to explore the mechanism of the catalytic performance enhancement by the functionalization Co 3 O 4 /GO surface with IL, the ORR process was theoretically studied by density functional theory (DFT) calculation (see details in supporting information). Considering the strong 311 crystal plane of Co 3 O 4 in the XRD pattern, a calculation model was established based on it with Co as the active center, and then the ORR process was simulated on Co 3 O 4 /GO and Co 3 O 4 /IL−GO surfaces [58–59] . The free energy diagrams show that the intermediate species adsorbed on Co 3 O 4 /IL−GO is more stable than that on Co 3 O 4 /GO.…”

Advanced Transition Metal‐Based OER Electrocatalysts: Current Status, Opportunities, and Challenges

“…For example, the surface active electron density of Co 3 O 4 can be effectively regulated by an argon ion radiation method. [ 112 ] The surface active electron density of Co 3 O 4 is upshifted, enhancing the adsorption capability to oxo group. As a result, the optimized catalyst only needs a small overpotential of 260 mV to reach 10 mA cm −2 .…”