Porous Ni Foams Filled by N-Doped Carbon Nanotubes Coated with N-Doped Ni₃P and Ni Nanoparticles for Catalytic Water Splitting

Abstract

The development of bifunctional catalysts possessing high efficiency and excellent stability was still a challenge as regards overall water splitting. Herein, a reasonable space division strategy of Ni foam (NF) was proposed to design a bifunctional catalyst. Ni-P alloy was loaded on carbon nanotubes (CNTs) through Pd-free electroless plating (Ni-P/CNTs). Subsequently, the Ni-P/CNT catalysts mixed with melamine were annealed for N doping. The N-doped CNTs coated with N-doped Ni3P and Ni nanoparticles (N-Ni3P-Ni/N-CNTs) were obtained. Finally, the N-Ni3P-Ni/N-CNTs were used as a filler to divide the pore size of NF by electroplating Ni, obtaining a network-like hierarchical porous electrode (N-Ni3P-Ni/N-CNTs/NF). This hierarchical porous structure exposed abundant catalytically active sites, facilitated the mass transfer, and prevented the catalyst agglomeration and corrosion that promote electrolyte contact and favor facile electron transfer kinetics. On the basis of the rational design, a self-supported N-Ni3P-Ni/N-CNTs/NF electrode showed a high specific surface area and exhibited superior electrocatalytic performances. The electrode achieved low overpotential of 73 and 270 mV at 10 mA cm–2 for the hydrogen and oxygen evolution reaction, respectively. Besides, it required a cell voltage of only 1.57 V to achieve 20 mA cm–2 when assembled in a 1 M KOH electrolyte for overall water splitting. Hence, this study represented a rational design of self-supported bifunctional electrode for overall water splitting.

WITHDRAWN: Prussian blue analogue derived nitrogen‒carbon mixed metal sulfides heterostructure for asymmetric supercapacitors

“…Figure 3 (e) shows the N 1s orbital spectrum. After Gaussian tting, it is found that there are mainly two forms of nitrogen, namely pyridine nitrogen at 399.4 eV and graphite nitrogen at 401.3 eV [24]. The C 1s spectrum (Fig.…”

Synthesis of Urchin-like Ni@NP@NCP Composites with Three Solvothermal Systems for Highly Efficient Overall Seawater Splitting

“…As shown in Figure b, the cell voltages can provide an overpotential as low as 1.697 V at the CD of 100 mA cm –2 in 1 M KOH alkaline conditions at room temperature, and 1.724 V at 100 mA cm –2 CD in alkaline simulated seawater. The performance of most non-precious metal electrolytic cells cannot do this (Figure c), as well as the precious metal catalyst electrolytic cell composed of commercial Pt/C//RuO 2 under the same conditions. − In particular, our electrolytic cells can generate a large CD of 300 mA cm –2 in alkaline simulated seawater (1 M KOH + 0.5 M NaCl) electrolyte at a voltage of 1.822 V, which is satisfactory to realize application for large current density at low voltage industrially.…”

Nitrogen‐Doped Electrocatalysts, and Photocatalyst in Water Splitting: Effects, and Doping Protocols

“…Therefore, the synergistic effect of the graphene and bimetallic sulfides was observed when the heterojunction established. The impact of dual N doping on the support, and transition metal compound was also examined to employ the N for adjusting the electronic structure of both ingredients [18b] . In this report, N‐CNT coated with N‐doped Ni 3 P and Ni nanoparticles (NPs) promoted the electrochemical water splitting, by which overpotentials of 73, and 270 mV for HER, and OER were resulted.…”

“…Post‐treatment N doping is the insertion of N after the creating electrocatalyst, which is carried out by one of the N saturations (type III) or thermal decomposition of the loaded N source (type IV). In type III, contacting excess amounts of N source leads to the doping of N atoms on the surface of the materials; in particular, N 2 and ammonia have been widely employed, such as annealing modified CNT under N 2 for the production of N‐CNT [18b] . Type IV is the most versatile strategy for N doping since abundant N‐containing materials could be uploaded on the desired compounds and subsequently decomposed by thermal treatment to leave N. For example, the NG part of MoS 2 −NiS 2 /NG was synthesized via immersing melamine sponge as the N source into GO suspension and burning the leached GO with melamine [16b] .…”