Exploiting highly active and bifunctional catalysts for both hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) is a prerequisite for the hydrogen acquisition. High‐entropy materials have received widespread attention in catalysis, but the high‐performance bifunctional electrodes are still lacking. Herein, a novel P‐modified amorphous high‐entropy CoFeNiCrMn compound is developed on nickel foam (NF) by one‐step electrodeposition strategy. The achieved CoFeNiCrMnP/NF delivers remarkable HER and HzOR performance, where the overpotentials as low as 51 and 268 mV are realized at 100 mA cm−2. The improved cell voltage of 91 mV is further demonstrated at 100 mA cm−2 by assessing CoFeNiCrMnP/NF in the constructed hydrazine‐assisted water electrolyser, which is almost 1.54 V lower than the HER||OER system. Experimental results confirm the important role of each element in regulating the bifuncational performance of high‐entropy catalysts. The main influencing elements seem to be Fe and Ni for HER, while the P‐modification and Cr metal may contribute a lot for HzOR. These synergistic advantages help to lower the energy barriers and improve the reaction kinetics, resulting in the excellent bifunctional activity of the CoFeNiCrMnP/NF. The work offers a feasible strategy to develop self‐supporting electrode with high‐entropy materials for overall water splitting.
The development of highly active bifunctional electrocatalysts for overall water splitting is of significant importance, but huge challenges remain. The key element depends on engineering the electronic structure and surface properties of material to achieve improved catalytic activity. Herein, a hierarchical nanowire array of metal sulfides heterostructure on nickel foam (FeCoNiSx/NF) was designed as a novel type of hybrid electrocatalyst for overall water splitting. The hybrid structure endowed plenty of catalytic active sites, strong electronic interactions, and high interfacial charge transferability, leading to superior bifunctional performance. As a result, the FeCoNiSx/NF catalyst delivered low overpotentials of 97 and 260 mV at the current density of 50 mA cm−2 for hydrogen and oxygen evolution reactions, respectively. Moreover, the FeCoNiSx/NF‐based water electrolyzer exhibited a small potential of 1.57 V for a high current density of 50 mA cm−2. These results indicate the promising application potential of FeCoNiSx/NF electrode for hydrogen generation. This work provides a new approach to develop robust hybrid materials as the highly active electrode for electrocatalytic water splitting.
Insulin-induced hyperpolarization of up to 9 mV has been described in isolated frog [J. Physiol. Lond. 252: 43-58, 1975; Am. J. Physiol. 251 (Cell Physiol. 4): C249-C254, 1979] and mammalian (Molecular Basis of Insulin Action, New York: Plenum, 1985, p. 451-463; Am. J. Physiol. 197: 524-526, 1959; Am. J. Physiol. 198: 1066-1070, 1960) skeletal muscle. We have shown that a similar hyperpolarization occurs in situ after administration of insulin in anesthetized rats. In streptozotocin (STZ)-treated rats, insulin produced approximately 66-70% of the hyperpolarization observed in normal rat skeletal muscle in situ. Administration of ouabain in situ blocked the insulin-induced hyperpolarization in the normal group of rats and significantly blunted the effect in the STZ group. These results suggest that insulin-induced hyperpolarization in skeletal muscle results from direct activation of the Na+-K+-ATPase pump. In isolated skeletal muscle from normal and STZ rats, there was no difference in the amount of the insulin-induced hyperpolarization. There was an additive, but small, hyperpolarizing effect of insulin and isoproterenol when administered in combination, suggesting that the greater magnitude of the insulin-induced hyperpolarization observed in situ in normal rats may be due to an additive effect of injected insulin and endogenous release of epinephrine. Alternatively, STZ treatment may directly alter the Na+-K+ pump so that its response to insulin is lessened.
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