Activating CoOOH Porous Nanosheet Arrays by Partial Iron Substitution for Efficient Oxygen Evolution Reaction

Abstract

Iron-substituted CoOOH porous nanosheet arrays grown on carbon fiber cloth (denoted as Fe Co OOH PNSAs/CFC, 0≤x≤0.33) with 3D hierarchical structures are synthesized by in situ anodic oxidation of α-Co(OH) NSAs/CFC in solution of 0.01 m (NH ) Fe(SO ) . X-ray absorption fine spectra (XAFS) demonstrate that CoO octahedral structure in CoOOH can be partially substituted by FeO octahedrons during the transformation from α-Co(OH) to Fe Co OOH, and this is confirmed for the first time in this study. The content of Fe in Fe Co OOH, no more than 1/3 of Co, can be controlled by adjusting the in situ anodic oxidation time. Fe Co OOH PNSAs/CFC shows superior OER electrocatalytic performance, with a low overpotential of 266 mV at 10 mA cm , small Tafel slope of 30 mV dec , and high durability.

Cation‐Modulated HER and OER Activities of Hierarchical VOOH Hollow Architectures for High‐Efficiency and Stable Overall Water Splitting

“…An extraordinarily low onset potential is calculated as 1.425 V (η 10 ) from VOOH‐Fe sample, which was significantly lower than the other four electrodes (VOOH‐5Fe: 1.472 V, VOOH‐1Fe: 1.477 V, VOOH‐10Fe: 1.479 V, and VOOH‐0Fe: 1.484 V). To the best of our knowledge, 195 mV overpotential versus 10 mA cm −2 is the best value reported for V or Fe (oxy)hydroxides and transcends many of the previously reported nonprecious metal OER catalysts, including Fe 0.5 V 0.5 OOH, Fe 0.33 Co 0.67 OOH, MoFe:Ni(OH) 2 /NiOOH, Co‐V hydr(oxy)oxide, F‐CoOOH/NF, CoS x /N‐doped graphene, etc. (Table S3, Supporting Information).…”

Heterostructures Composed of N‐Doped Carbon Nanotubes Encapsulating Cobalt and β‐Mo2C Nanoparticles as Bifunctional Electrodes for Water Splitting

“…[38,39] Theoverpotential h is obtained according to Equation (5): [38,39] Theoverpotential h is obtained according to Equation (5):…”

“…[38] Fort he Co/b-Mo 2 C@N-CNTs,t he overpotential at the Co site adjacent to b-Mo 2 Ci sd ecreased to 0.09 V( DG 3 = 1.32 eV; Figure 4f), which suggests that the heterointerface created by Co and b-Mo 2 Ci sa ble to lower the overpotential at the Co sites and further promote electrocatalytic activity for the OER, thus resulting in entirely improved catalytic performance. [38] Fort he Co/b-Mo 2 C@N-CNTs,t he overpotential at the Co site adjacent to b-Mo 2 Ci sd ecreased to 0.09 V( DG 3 = 1.32 eV; Figure 4f), which suggests that the heterointerface created by Co and b-Mo 2 Ci sa ble to lower the overpotential at the Co sites and further promote electrocatalytic activity for the OER, thus resulting in entirely improved catalytic performance.…”

Defect‐Rich Heterogeneous MoS2/NiS2 Nanosheets Electrocatalysts for Efficient Overall Water Splitting

“…[9,10] Element doping would be an effective method to improve the catalytic activities, such as doping Ni atoms in MoS 2 . [11][12][13][14][15] As for tuning the morphology, constructing 2D TMS nanosheets could generate abundant electroactive sites because of inherent large specific surface and rich active edges. [11][12][13][14][15] As for tuning the morphology, constructing 2D TMS nanosheets could generate abundant electroactive sites because of inherent large specific surface and rich active edges.…”

“…Since electrochemical reactions mainly occur on the surfaces or at the interfaces of electrocatalysts, [11][12][13] it is vital to investigate the surface states of obtained samples by Raman and XPS measurements. As shown in Figure 3a, the peaks at about 294, 375, and 404 cm −1 belong to E 1g, E 1 2g , and A 1g modes of 2H-MoS 2 , and the peak 345 cm −1 is from the modes of the Ni-S. [8,[27][28][29] More importantly, the obvious three peaks in 800-1000 cm −1 could be ascribed to the molecular structure of Mo 3 S 13 that existing the edge sites of MoS 2 , and further suggest rich under-coordinated Mo-S edge sites in MoS 2 /NiS 2 -3 nanosheets.…”