Hydrazine-assisted electrochemical hydrogen production by efficient and self-supported electrodeposited Ni-Cu-P@Ni-Cu nano-micro dendrite catalyst

The emergence of high-performance noble metal-free electrodes in water splitting operations to produce hydrogen is of paramount importance to generate new energy in the future. The oxygen evolution reaction (OER) in water splitting is a slow reaction that consumes much energy to produce hydrogen, and generally, replacing an anodic reaction with less thermodynamic potential can significantly improve the efficiency of hydrogen production. The hydrazine oxidation reaction (HzOR) can be a great alternative to OER. We describe the fabrication of Ni-Cu-P@Ni-Cu nano-micro dendrite using a simple electrodeposition method. The developed Ni-Cu-P@Ni-Cu is used as a bifunctional electrode for hydrogen evolution reaction (HER) and HzOR. The high active electrochemical area, the porous structure and the penetration of electrolyte into the pores, the synergistic effect between Ni and Cu, and the rapid separation of the bubbles created from the surface led to the creation of an electrode with excellent electrocatalytic activity. The HER and HzOR processes required only -70 mV vs.RHE and 3.88 mV vs.RHE potentials in 1.0 M KOH and 1.0 M KOH + 0.5 M N2H4, respectively, to generate a current density of 10 mA.cm−2. Also, a very low potential of 125 mV was required in the hybrid overall water electrolysis system. This study presents a new, cost-effective, versatile, and industrial strategy to fabricate three-dimensional electrocatalysts. © 2021 Elsevier Ltd1

Ultra-fast electrochemical preparation of Ni-Cu-Fe nano-micro dendrite as a highly active and stable electrocatalyst for overall water splitting

The development of highly active, durable, and low-cost electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) to advance the commercial applications of overall water electrolysis is regarded as a crucial matter. We describe an ultra-fast synthesis of multi-metal Ni-Cu-Fe micro-nano dendritic electrocatalysts were synthesized on nickel foam using a simple one-step constant current electrodeposition method. According to DFT simulations, Fe incorporation causes a downshift movement in the d-band center and the formation of additional catalytic active sites. Ni-Cu-Fe nano-micro dendrites have potential applications as bifunctional catalysts for electrochemical water splitting. Also, the increased electrical conductivity of the Ni-Cu-Fe electrode is due to the placement of more electronic states near the Fermi level and creating an optimal and porous dendritic structure that causes better electrolyte penetration in the pores. Experiments show that in the 1.0 M KOH electrolyte, Ni-Cu-Fe catalysts need an ultra-low overpotentials of 42 mV and 300 mV to supply a current density of −10 mA cm−2 for the HER and 50 mA cm−2 for the OER. Also, when Ni-Cu-Fe electrocatalyst is used as a bifunctional electrode in the overall water splitting system, it displays a low cell voltage of 1.54 V in a current density of 10 mA cm−2 can maintain this activity for more than 100 h. © 2023 Elsevier LtdFALS