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• The electronic configuration of CoFe–BDC is optimized by introducing 4-nitrobenzoic acid. • The uncoordinated metal sites in CoFe–BDC NO 2 expose more active centers. • The CoFe–BDC NO 2 follows the LOM during OER with Co-O-Fe bond formation. • CoFe–BDC NO 2 exhibits excellent activity and long-term durability in alkaline media. • CoFe–BDC NO 2 /NF also has excellent water splitting and CO 2 RR performance by MEA testing. The rational design of metal-organic frameworks (MOFs) provides potential opportunities for improving energy conversion efficiency. However, developing efficient MOF-based electrocatalysts remains highly challenging. Herein, a strategy involving strain engineering is developed to promote the electrocatalytic performance of MOFs by optimizing electronic configuration and improving the active site. As expected, the optimized CoFe–BDC NO 2 exhibits a low overpotential of 292 mV at 10 mA cm–2 and a small Tafel slope of 31.6 mV dec–1 as oxygen evolution reaction (OER) electrocatalyst. Notably, when CoFe–BDC NO 2 is prepared on Nickel foam (NF), the overpotential is only 345 mV at 1 A cm–2, which ensures efficient water oxidation properties. Integrating CoFe–BDC NO 2 /NF anode in membrane electrode assembly (MEA) for overall water splitting and CO 2 reduction reaction (CO 2 RR) tests, the results show that the cell voltages of CoFe–BDC NO 2 /NF are 3.14 and 3.09 V at 300 mA cm–2 (25 °C), respectively, indicating that MOFs have various practical application prospects. The research of the structure-performance relationship reveals the lattice oxygen oxidation mechanism (LOM) where the Co-O-Fe bond is formed during the OER process by changing the electronic environment and coordination structure of CoFe–BDC NO 2 , and with high valence Co as active center, which provides a deep understanding of the structure design of MOFs and their structural transformation during OER. [Display omitted] [ABSTRACT FROM AUTHOR]

The nanoporous amorphous-rich A-RuMnOxaerogel electrocatalyst was fabricated by the controlled oxidation of RuMn aerogels. The results demonstrate that the amorphous structure can effectively weaken the Ru–O covalency, optimize the adsorption path, and reduce the energy barriers of rate-determining step, which jointly promote the activity and stability.

Metal-organic frameworks (MOFs) exhibit excellent application potential in the field of electrocatalysis. In this study, we first prepare MIL-100 nanosheets on nickel foam (MIL-100/NF) and then successfully anchor Ag nanoparticles (NPs) on the nanosheets (Ag@MIL-100/NF) for oxygen evolution reaction (OER) catalysis. This strategy dramatically improves the conductivity of MIL-100 and the Ag NPs are uniformly dispersed on the nanosheets. The Ag@MIL-100/NF catalyst has excellent electrocatalytic performance and long-term corrosion resistance, with a low overpotential of 207 mV and a long-term stability of at least 100 h at a current density of 50 mA·cm−2. The experimental results demonstrate that this high OER catalytic performance is due to the improved charge transfer after loading Ag NPs, the combination of nanosheets and highly dispersed Ag NPs that expose more active sites and the adjusted chemical valence states of Fe and Ni in MIL-100. This work provides a surface decoration approach for the preparation of excellent catalysts directly used in the OER.

In this work, a method for synthesizing AgO exposed with different planes by electrodeposition using an unbuffered solution and a complexing agent as an electrolyte was first proposed. The experimental results indicate that the oxygen evolution activity of AgO crystal exhibits very obvious facet-dependent properties. AgO crystals with mainly {1̅11} exposed faces yield a superior catalytic activity over those with mainly {2̅02} exposed faces under electrochemical water oxidation conditions, which agrees with the theoretical calculations. The AgO film with dominant {1̅11} facets has a modest overpotential of 418 mV and its catalytic performance is demonstrated by long-term electrolysis at 2.03 V versus a reversible hydrogen electrode in a near-neutral potassium phosphate solution. A stable current density of 3.7 mA cm–2persists for at least 6 h, and a Faradaic efficiency of 93% is obtained, which is much better than other Ag-based electrodes, especially current densities.

Metal–organic frameworks (MOFs) as promising electrocatalysts have been widely studied, but their performance is limited by conductivity and coordinating saturation. This study proposes a cationic (V) modification strategy and evaluates its effect on the electrocatalytic performance of CoFe–MOF nanosheet arrays. The optimal V–CoFe–MOF/NF electrocatalyst exhibits excellent oxygen-evolution reaction (OER)/hydrogen-evolution reaction (HER) performance (231 mV at 100 mA cm–2/86 mV at 10 mA cm–2) in alkaline conditions, with its OER durability exceeding 400 h without evident degradation. Furthermore, as a bifunctional electrocatalyst for water splitting, a small cell voltage is achieved (1.60 V at 10 mA cm–2). The practicability of the catalyst is further evaluated by membrane electrode assembly (MEA), showing outstanding activity (1.53 V at 10 mA cm–2) and long-term stability (at 300 mA cm–2). Moreover, our results reveal the apparent reconstruction properties of V–CoFe–MOF/NF in alkaline electrolytes, where the partially dissolved V promotes the formation of more active β-MOOH. The mechanism study shows the OER mechanism shifts to a lattice oxygen oxidation mechanism (LOM) after V doping, which directly avoids complex multistep adsorption mechanism and reduces reaction energy. This study provides a cation mediated strategy for designing efficient electrocatalysts.

Nanostructured mesoporous NiCo2O4, Co3O4and NiO spinel oxides were prepared through the hydroxide coprecipitation method using EG (ethylene glycol) as solvent without any template. The NiCo2O4powders were analyzed by TGA, XRD, N2adsorption-desorption, SEM and EDS. And the electrocatalytic properties of NiCo2O4/Ti, Co3O4/Ti and NiO/Ti electrodes for oxygen evolution in 0.1 mol/L KOH (pH = 13) were tested by cyclic voltammetry, Tafel curves and electrolysis. The result shows that NiCo2O4/Ti electrode has higher electrocatalytic activity in oxygen evolution reaction than Co3O4/Ti and NiO/Ti electrodes. NiCo2O4/Ti electrode prepared at 350 °C has the highest apparent current density and the highest true current density. The Tafel slope of NiCo2O4/Ti electrode prepared at 350 °C is 68.49 mV/dec.