ChemInform Abstract: Hierarchical Zn_xCo_3‐xO₄ Nanoarrays with High Activity for Electrocatalytic Oxygen Evolution.

Abstract

Hierarchical ZnxCo3-xO4 Nanoarrays with High Activity for Electrocatalytic Oxygen Evolution. -Zn x Co 3-x O 4 nanoarrays are grown hydrothermally on Ti foils using appropriate ratios of Zn(NO3)2 and Co(NO3)2, NH4F and Co(NH2)2 in H2O together with the Ti substrate (autoclave, 120°C, 10 h). High O2 evolution reaction (OER) performance is achieved from these nanostructures which consist of small secondary nanoneedles grown on primary rhombus-shaped pillar arrays. The nanostructures show a large roughness, high porosity, and a high density of active sites. The samples produced from a 1:3 mixture of Zn(NO3)2 and Co(NO3)2 exhibits a small overpotential of ≈0.32 V at a current density of 10 mA/cm 2 and a Tafel slope of 51 mV/decade. The nanostructures perform significantly better than pure Co3O4 and a commercial Ir/C catalyst and belong to the best OER catalysts reported for alkaline media indicating that they are promising water splitting electrodes. -(LIU, X.; CHANG, Z.; LUO, L.; XU, T.; LEI, X.; LIU*, J.; SUN, X.; Chem. Mater. 26 (2014) 5, 1889-1895, http://dx.doi.org/10.1021/cm4040903 ; State Key Lab. Chem. Resour. Eng., Beijing Univ.

ZIF 67 Based Highly Active Electrocatalysts as Oxygen Electrodes in Water Electrolyzer

“…However, if Zn was also present in the system, a Fe/Ni/Zn synergistic effect may occur that aids in faster OH − adsorption, supported by the lower FeNiO NP@ZnCo ZIF and ZnCo ZIF Tafel slope. Zinc is known to increase the electrophilicity of Co sites that aids in faster adsorption of OH − ions, as observed previously, 41 and, hence, may explain the observed decrease in the Tafel slope in the case of FeNiO NP@ZnCo ZIF. A similar trend in Tafel slope was also observed by Zhou et al where addition of Zn in nickel based hydroxides resulted in the lowering of Tafel slope compared to that of bare Ni hydroxide nanoarrays.…”

Superwetting Electrodes for Gas-Involving Electrocatalysis

“…14 This phenomenon can also be observed on other GERs, such as OER, HzOR, and ClER. For OER, we found that the threedimensional NiFe-LDH nanoarrays 24 and hierarchical Zndoped Co 3 O 4 nanostructures 25 directly constructed on Ni foam showed a superior OER performance to the colloidal counterparts, which is attributed to both the high intrinsic activity and superaerophobic property. As for the HzOR, we chose Cu as the catalyst and constructed a Cu nanoarray film for high rate HzOR.…”

Bifunctional Electrodeposited 3D NiCoSe2/Nickle Foam Electrocatalysts for Its Applications in Enhanced Oxygen Evolution Reaction and for Hydrazine Oxidation

“…31 Peak broadening and the appearance of an additional oxidation peak in the case of NiCoSe 2 /NF could be assigned to the transformation of Co II to Co III and Co III to Co IV . 32 In fact, this peak broadening is beneficial because it advocates the presence of additional active sites in NiCoSe 2 /NF compared with bare NF. Furthermore, the rapid increment in the peak current density of NiCoSe 2 /NF is indicative of its much larger active surface area along with the presence of numerous catalytically active centers for OER.…”