Zhaojun Tan,Shuaihui Guo,Wen Wang,Gang Li,Zhenwei Yan
Precise catalyst design is essential in the electrolysis of water to deliver clean energy, where the challenge is to construct highly active sites at the electrocatalyst interface. In this study, CoPVP/NFF (NiFe foam) and Mo–CoPVP/NFF precursors were synthesized sequentially in a hydrothermal procedure using NiFe foam as substrate with the ultimate formation of a NiFeCoMoS/NFF electrocatalyst by vulcanization at 350°. The NiFeCoMoS/NFF system exhibits a complex 1D–2D–3D composite structure with 1D nanoparticles attached to a 2D nano-paper on the surface of the 3D NiFe foam. The overpotentials associated with hydrogen and oxygen evolution by NiFeCoMoS/NFF are 123 mV and 245 mV, respectively, at a current density of 10 mA cm−2. A three-electrode system using NiFeCoMoS/NFF as working and counter electrode has been assembled that can generate current densities of 100 mA cm−2 at voltages of 1.87 V. Theoretical (DFT) calculations have shown that NiFeCoMoS/NFF exhibits favorable H adsorption energetics and a low OER reaction barrier. This study has identified a viable means of enhancing the efficiency of water electrolysis by regulating catalyst surface structure.
Developing efficient and nonprecious electrocatalysts for oxygen evolution reaction (OER) is crucial for the hydrogen generation via water splitting. Here we report the direct growth of heterostructural Ni 2 P–Fe 2 P hybrid electrocatalysts on NiFe foams. The redox engineered NiFe foam (rNF) significantly enhances the OER performance. Among prepared catalysts, Ni 2 P–Fe 2 P/rNF performs the highest OER activity, driving the current densities of 10 and 100 mA cm −2 at low overpotentials of 218 and 270 mV in 1 M KOH, respectively. Meanwhile, it can maintain 100 mA cm −2 for 24 h without obvious degradation. The morphology and composition of NFP/rNF after OER test were carefully studied. This work suggests that self-supported bimetal phosphides of NFP/rNF is an efficient and durable electrode material for water oxidation .
Huajun Zhou,Yuzhen Zhang,Chenxi Shi,Kai Yuan,Rui Zhou,Peihua Zhao,Yongping Qu,Yanzhong Wang
Efficient and inexpensive oxygen evolution reaction (OER) catalysts are essential for the electrochemical splitting of water into hydrogen fuel. Herein, we have successfully synthesized NiCoFe(OH) x nanosheets on Ni-Fe foam (NFF) by exploiting the Fenton-like effect of Co 2+ and S 2 O 8 2− to corrode the NFF foam. The as-prepared NiCoFe(OH) x /NFF exhibits the porous structure with the interconnected nanosheets that are firmly bonded to the conductive substrate of NFF, thereby enhancing ions and charge transfer kinetics. The unique structure and composition of NiCoFe(OH) x /NFF result in the low overpotentials of 200 and 262 mV at current densities of 10 and 100 mA cm −2 , respectively, as well as a low Tafel slope of 53.25 mV dec −1 . In addition, NiCoFe(OH) x /NFF displays low overpotentials of 267 and 294 mV at a high current density of 100 mA cm −2 in simulated and real seawater, respectively. Furthermore, the assembled NiCoFe(OH) x //Pt/C water electrolysis cell has achieved a current density of 10 mA cm −2 at a low voltage of 1.49 V, and displayed the good stability with slight attenuation for 110 h. The high OER performance of NiCoFe(OH) x is attributed to the co-catalytic effect of the three metal ions and the interconnected porous nanosheet structure.
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