Self-derivation-behaviour of substrates realizing enhanced oxygen evolution reaction

Facile method to activate substrate for oxygen evolution by a galvanic-cell reaction

NiFe layered double hydroxide (NiFe LDH) is a promising material with multiple functions. In this communication, a novel method is used to prepare NiFe LDH. This synthesis method is achieved via galvanic-cell corrosion between nickel and iron substrates in aqueous solutions containing a halogen group anion (e.g., Cl) at ambient temperature. The as-prepared NiFe LDH electrodes are developed as electrocatalysts for the oxygen evolution reaction (OER) and exhibit excellent catalytic activities and durability. This work provides an energy-efficient, cost-effective, and scaled-up corrosion engineering approach for manufacturing NiFe LDH materials.

Acid etching followed by water soaking: a top-down strategy to induce highly reactive substrates for electrocatalysis

A top-down strategy using acid etching followed by water soaking is utilized to in situ synthesize autologous NiFe LDH nanosheets on NiFe foam without other metal ions, oxidizing agents or heating steps. The NiFe foam serves as both the metal source and substrate, and the obtained nanosheets are firmly anchored on the foam. The obtained ultrathin nanosheet arrays could greatly increase the electrocatalytic active sites. This factor together with the synergistic effect between Fe and Ni simultaneously leads to an enhanced catalytic effect for water splitting and urea oxidation. This strategy could be scaled up to pave a viable way for low-cost fabrication of highly efficient electrodes for electrocatalysis.

Surface Reconstruction of an FeNi Foam Substrate for Efficient Oxygen Evolution

Designing earth-abundant electrocatalysts that are highly active, low-cost, and stable for the oxygen evolution reaction (OER) is crucial for electrochemical water splitting. However, in conventional electrode fabrication strategies, NiFe layered double hydroxide (NiFe LDH) catalysts are usually coated onto substrates as external components, which suffers from poor conductivity, easily detaches from the substrate, and hinders their long-term utilization. Herein, the surface-reconstruction strategy is used to synthesize in situ autologous NiFe LDH to increase the surficial active sites numbers. The FeNi foam (FNF) serves as both the metal source and substrate, and the obtained NiFe LDH nanosheets (NSs) are firmly anchored in the monolithic FNF. What needs to be emphasized is that the strategy does not involve any high-temperature or high-pressure processes, apart from a cost-effective etching and a specified drying treatment. The nanostructure of NiFe LDH and the synergistic effect between Fe and Ni simultaneously lead to an enhanced catalytic effect for the OER. Remarkably, the sr-FNF46 requires only an ultralow overpotential of 283 mV to achieve a current density of 100 mA cm^-2 for the OER in 1 M KOH electrolyte, and exhibits excellent stability. Thus, the obtained electrode holds promise for electrocatalytic applications. Finally, the formation mechanism of NiFe LDH NSs due to surface reconstruction is investigated and discussed in detail.

Multi-shelled hollow layered double hydroxides with enhanced performance for the oxygen evolution reaction

Hollow materials with a sophisticated structure are promising for various applications with boosted performances and innovative properties. Herein, we report an in situ transformation strategy using multi-layered MOFs as templates to fabricate multi-shelled hollow NiZnCoFe layered double hydroxides (LDHs), which outperformed the double- and single-shelled hollow LDHs and commercial IrO₂ in the oxygen evolution reaction.

Boron-modulated surface of hollow nickel framework for improved hydrogen evolution

A hollow Ni framework (HNF) is designed and prepared to utilize the exterior and interior surface active sites of a Ni-based binder-free and support-free electrode. Furthermore, the more efficient Ni-B active sites are then in situ introduced on the surface of HNF. This micro/nano structure engineering, together with the surface boron modulation, results in a synergistically enhanced catalytic effect for the HER performance.