Engineering Pyrite-Type Bimetallic Ni-Doped CoS2 Nanoneedle Arrays over a Wide Compositional Range for Enhanced Oxygen and Hydrogen Electrocatalysis with Flexible Property

Abstract

Abstract:The development of cheap and efficient catalytic electrodes is of great importance, to promote the sluggish overall water-splitting systems associated with the large-scale application of clean and renewable energy technologies. In this work, we report the controlled synthesis of pyrite-type bimetallic Ni-doped CoS 2 nanoneedle (NN) arrays supported on stainless steel (SS) (designated as Ni x Co 1−x S 2 NN/SS, 0 ≤ x ≤ 1) and the related compositional influence on electrocatalytic efficiencies for the oxygen and hydrogen evolution reaction (OER/HER). Impressively, the Ni 0.33 Co 0.67 S 2 NN/SS displays superior activity and faster kinetics for catalyzing OER (low overpotential of 286 mV at 50 mA cm −2 ; Tafel value of 55 mV dec −1 ) and HER (low overpotential of 350 mV at 30 mA cm −2 ; Tafel value of 76 mV dec −1 ) than those of counterparts with other Ni/Co ratios and also monometallic Ni-or Co-based sulfides, which is attributed to the optimized balance from the improved electron transfer capability, increased exposure of electrocatalytic active sites, and favorable dissipation of gaseous products over the nanoneedle surface. Furthermore, the conductive, flexible SS support and firmly attached in-situ integrated feature, result in the flexibility and remarkable long-term stability of as-prepared binder-free Ni 0.33 Co 0.67 S 2 NN/SS electrode. These results demonstrate element-doping could be an efficient route at the atomic level to design new materials and further optimize the surface physicochemical properties for enhancing the overall electrochemical water splitting activity.

Host-Guest Engineering of Layered Double Hydroxides towards Efficient Oxygen Evolution Reaction: Recent Advances and Perspectives

“…Electrochemical water splitting holds great promise for clean energy resources and has aroused broad study interest in recent years [1][2][3][4][5]. Among all the studies, the development of electrocatalysts for the anode oxygen evolution reaction (OER) is one of the key issues to decrease the overpotential of practical water splitting due to its sluggish four-electron process [6][7][8][9][10]. It is well-known that ruthenium and iridium oxides demonstrate high activity for water oxidation in acid and alkaline electrolytes, respectively [11,12].…”

A Morphologically Engineered Robust Bifunctional CuCo2O4 Nanosheet Catalyst for Highly Efficient Overall Water Splitting

“…Figure a shows the polarization curve of the fabricated bifunctional CCO nS || CCO nS nanocatalyst electrolyser. It reveals that the CCO nS || CCO nS bifunctional catalyst could provide 10 mA cm −2 current density to deliver the full‐cell voltage of 1.64 V, which is favorably comparable with various state‐of‐the‐art water‐based alkaline electrolysers (Figure b) . Although the NiFeMo(OOH) attained the lowest cell voltage of 1.45 V, its activity was decayed initially during stability and then this electrolyser maintained a voltage of 1.6 V throughout the bifunctional full‐cell stability.…”

Novel Stable 3D Stainless Steel‐Based Electrodes for Efficient Water Splitting

“…The OxCNT/SS, CNT/SS, bare SS, and 20 wt% Pt/C/SS exhibited overpotentials of 257, 334, 359, and 82 mV, respectively. The as‐prepared Pt/OxCNT/SS exhibits the best HER performance when compared to other SS‐based electrodes recently reported in the literature as summarized in Table S3 (Supporting Information) . From the corresponding Tafel plots (Figure f), the Tafel slopes for bare SS, CNT/SS, and OxCNT/SS are 126, 120, and 106 mV dec −1 , respectively.…”