Promotion of the Electrocatalytic Oxygen Evolution Reaction by Chemical Coupling of CoOOH Particles to 3D Branched γ-MnOOH Rods

Abstract

The chemical-coupled three-dimensional (3D) γ-MnOOH with CoOOH particles (γ-MnOOH/CoOOH) was fabricated through a two-step strategy involving a hydrothermal and reduction–oxidation process. The strong solid–solid interfacial interactions between γ-MnOOH rods and CoOOH particles feature the Mn–O–Co bond on the interface and a high valence state of cobalt in CoOOH. The branched γ-MnOOH/CoOOH composites demonstrate a significantly strengthened synergy effect for the oxygen evolution reaction (OER). The optimal B-MCO-0.1 (γ-MnOOH/CoOOH-0.1) shows an excellent OER performance, which requires an overpotential of 313 mV to reach the current density of 10 mA cm–2 with a lower Tafel slope (87 mV dec–1) and the strong durability in alkaline electrolyte. Specially, the intrinsic OER activity (versus electrochemical active surface area, ECSA) on B-MCO-0.1 at an overpotential of 420 mV is 16.3 and 8.9 times higher than those of γ-MnOOH and CoOOH, respectively. The results demonstrate that OER activity originates mainly from the interfacial coupling of γ-MnOOH and CoOOH. Our work highlights the vital function of the interfacial interactions in modulating the electronic structure of the active sites and suggests an effective avenue to rationally design highly active electrocatalysts.

NiCo2O4‐Based Nanosheets with Uniform 4 nm Mesopores for Excellent Zn–Air Battery Performance

“…Furthermore, as presented in Figure S11 in the Supporting Information, the Faraday capacitance of the NiCo 2.148 O 4 PNSs significantly increased after 10 CV cycles, which indicated the enhanced surface reconstruction. [ 39 ] The changes in the O 1s XPS profile [ 40 ] (Figure S12a, Supporting Information) and supplementary peak at ≈680 cm −1 in the Raman spectra [ 41 ] (Figure S12b, Supporting Information) of the NiCo 2.148 O 4 PNSs after the OER further confirmed the surface reconstruction.…”

Synthesis of 3D IrRuMn Sphere as a Superior Oxygen Evolution Electrocatalyst in Acidic Environment

“…Herein, we report the preparation of 3D IrRuMn spheres through a wet chemical method. The well‐organized nanospheres have 3D accessible sites and a maximized surface area, which enhances the electrochemical performance . As a result, the as‐prepared 3D IrRuMn demonstrates remarkable electrocatalytic performance for the OER in acidic conditions with a very small overpotential of 260 mV vs. RHE required to drive a current density of 10 mA cm −2 .…”

A Redox-Additive Electrolyte and Nanostructured Electrode for Enhanced Supercapacitor Energy Density

“…The higher Ni 3+ concentration supports that there is surface NiOOH . In the detailed Co 2p spectrum (Figure E), the presence of Co 3+ is associated with the peaks at 780.3 and 795.5 eV; meanwhile, the two peaks located at 782.5 and 796.7 eV are assigned to Co 2+ . − The higher Co 3+ concentration also supports that there is surface CoOOH. ,, The surfaces NiOOH and CoOOH contribute to the capacitance due to the redox reactions described in eqs and , respectively , …”

“…38−40 The higher Co 3+ concentration also supports that there is surface CoOOH. 39,41,42 The surfaces NiOOH and CoOOH contribute to the capacitance due to the redox reactions described in eqs 2 and 3, respectively 43,44…”