Hierarchical Zn‐Doped CoO Nanoflowers for Electrocatalytic Oxygen Evolution Reaction

Abstract

Hierarchical Zn-doped CoO nanoflowers have been prepared using their hydroxides as precursors. The nanoflowers are assembled by dozens of 2D nanoplates. Each nanoplate is formed by numerous Zn-doped CoO nanoparticles. Zn-doped CoO catalyst is highly efficient for electrocatalytic water oxidation with a low overpotential (η = 293 mV at j = 10 mA cm À 2 ) and long-term stability, which is comparable to the commercial RuO 2 catalysts in alkaline media. The 3D hierarchical structure provides abundant surface catalytic sites, while the density functional theory (DFT) calculations show that the Zn doping is also beneficial for the enhanced oxygen evolution reaction (OER) activities. This series of novel hierarchical porous nanoflowers is a promising anode material for water oxidation.

Tuning the intrinsic catalytic activities of oxygen-evolution catalysts by doping: a comprehensive review

“…Among doped series, composition with Ni 0.3 Co 0.7 O catalyst displays highest OER activity with e g value of ~1.3. Huo et al reported improved OER performance of CoO nanoflowers by doping with Zn 106. DFT study confirmed that OER active sites were increased by Zn doping, and high surface area of nanoflowers was another contributor to the improved catalytic activity.…”

Synthesis of 2D cobalt oxide nanosheets using a room temperature liquid metal

“…However in terms of the less studied CoO x material, the performance is slightly better than CoO nanobers 52 in terms of overpotential at 10 mA cm À2 and comparable to previous reports of CoO nanomaterials which were investigated in a more concentrated alkaline electrolyte of 1 M KOH, compared to 0.1 M used here, which gave values of 400 mV for both nanoparticles 53 and nanoplates. 54 Again the activity of CoO can be improved via doping with a second metal such as Fe 52 and Zn 54 but this was not the goal of the current study.…”

Trimetallic Sulfide Hollow Superstructures with Engineered d‐Band Center for Oxygen Reduction to Hydrogen Peroxide in Alkaline Solution

“…Compared with CoS x , the binding energy of Co 2P 3/2 orbital of Co 3+ in ZnCoS (779.17 eV) presents a negative shift of 0.26 eV and the Co 3+ /Co 2+ ratio increases to 4.7/1, similar to the reported Zn‐doped cobalt compounds. [ 36 , 37 ] In contrast, by further incorporating Ti element, the Co 2P 3/2 peak (779.31 eV) shifts toward higher binding energy, and the Co 3+ /Co 2+ ratio decreases from 4.7/1 to 3.7/1 due to the electron density shift from Ti to Co center, [ 38 , 39 ] which locates between ZnCoS and CoS x . When increasing the Co/Zn ratio, the binding energy of Co 2P 3/2 (≈779.39 eV) in Ti–ZnCoS HSS‐1 further increases.…”