NiSe2 nanowire (NW) arrays grown on flexible carbon fiber paper (CFP) were synthesized, for the first time, through a novel thermal selenization method in vacuum instead of flowing inert gas. The ultrathin NiSe2 NWs uniformly cover the CFP, contributing to the large surface area and fast charge transportation. Desirably, this binder-free and hierarchical electrode shows favorable activity for hydrogen evolution reaction (HER). It only requires an overpotential of 172 mV to afford the current density of 100 mA cm–2 in 0.5 M H2SO4, corresponding to a low Tafel slope of 32.44 mV dec–1. After 1000 continuous cycles, the HER activity of NiSe2 NWs is well-maintained. Moreover, the current density remains unchanged in prolonged electrolysis, indicating an excellent durability of NiSe2 NWs. The novel preparation method described in this study could inspire future work on the synthesis of transition-metal dichalcogenides with high purity and ultrasmall nanostructure toward improved electrocatalytic activity.
Hengjie Qin,Ying Lv,Ping Li,Meixia Xiao,Haiyang Song,Qian Zhang,Jialun Yang
A series of Bi2Se3@C materials were prepared through a bismuth metal organic framework (CAU-17) assisted hydrothermal selenization method followed by carbonization, which have been found to be useful as electrode materials for supercapacitor application. The Bi2Se3@C obtained below 500 °C seems to show an excellent specific capacity of 565.9 C g−1 at a current density of 1 A g−1. Furthermore, the performance of Bi2Se3@C in symmetrical supercapacitors (SSCs) is also systemically investigated, and the SSC device achieves a maximum energy density of 39.3 W h kg−1 at a power density of 639.9 W kg−1 and maintains 90.5% of this capacity over 1000 cycles.
Qimin Peng,Xiaoling Zhuang,Longgui Wei,Luyan Shi,Tayirjan Taylor Isimjan,Ruobing Hou,Xiulin Yang
Graphical A thorny challenge : A nanothorn-like superhydrophilic Nb−CoSe 2 /CC (CC=carbon cloth) catalyst is fabricated through a facile in-situ hydrothermal selenization and Ar annealing strategies. The catalyst illustrates an excellent oxygen evolution activity (297 mV at 200 mA cm −2 ), outstanding long-term durability, and good overall water splitting performance (1.93 V at 500 mA cm −2 ). Developing cost-effective, highly active, and robust electrocatalysts for oxygen evolution reaction (OER) at high current density is a critical challenge in water electrolysis since the sluggish kinetics of the OER significantly impedes the energy conversion efficiency of overall water splitting. Here, a 1D nanothorn-like Nb−CoSe 2 /CC (CC=carbon cloth) structure was developed as an efficient OER catalyst. The optimized Nb−CoSe 2 /CC catalyst exhibited remarkable OER performance with the low overpotentials of 220 mV at 10 mA cm −2 and 297 mV 200 mA cm −2 and a small Tafel slope (54.1 mV dec −1 ) in 1.0 m KOH electrolyte. More importantly, the Nb−CoSe 2 /CC electrode displayed superior stability after 60 h of continuous operation. In addition, cell voltages of 1.52 and 1.93 V were required to achieve 10 and 500 mA cm −2 for the electrolyzer made of Nb−CoSe 2 /CC (anode) and the Pt/C (cathode). Density functional theory (DFT) calculations combined with experimental results revealed that incorporating niobium into the CoSe 2 could optimize the adsorption free energy of the reaction intermediates and enhance the conductivity to improve the catalytic activity further. Additionally, the super-hydrophilicity of Nb−CoSe 2 /CC resulting from the surface defects increased the surface wettability and facilitated reaction kinetics. These results indicate that Nb−CoSe 2 /CC intrinsically enhances OER performance and possesses potential practical water electrolysis applications.
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