Electrodeposited nickel-sulfide films as competent hydrogen evolution catalysts in neutral water

Abstract

The development of low-cost, efficient, and robust electrocatalysts of the hydrogen evolution reaction (HER) is a crucial step toward the conversion and storage of sustainable and carbon-neutral energy resources, such as solar energy. Not only the HER catalysts need to be composed of inexpensive elements, they are also desirable to be prepared at low energy cost. In this work, we report that nickelsulfide (Ni-S) films prepared by facile potentiodynamic deposition are active HER catalysts in aqueous media. Notably, the Ni-S films showed catalytic activity in water with a wide range of pH values (0 to 14), as well as in natural water. In pH 7 phosphate buffer, a current density of 60 mA cm À2 could be achieved with a Tafel slope of 77 mV dec À1 and a Faradaic efficiency of 100%. A long-term bulk electrolysis of the Ni-S film exhibited steady current over 100 h with no deactivation, demonstrating its superior stability in neutral water. Further, an initial activation process was observed, which is likely due to the increase in the effective surface area of the Ni-S film under electrocatalytic conditions. A suite of characterization techniques, including X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, were conducted to probe the composition and structure of the Ni-S film, revealing that its major component is Ni 3 S 2 which was preserved under electrocatalytic conditions.

Enhancement of the Hydrogen Evolution Reaction from Ni-MoS2 Hybrid Nanoclusters

“…This would indicate that under air exposure the doping Ni atoms spontaneously increase their oxidation state to Ni 2+ as found in NiO species, agreeing with the behavior observed for bare Ni nanoclusters. Presence of a nickel sulfide phase cannot be discarded from XPS results as it is well reported that directly bonded S atoms leave the Ni 2p 3/2 peak position unaltered, 28 and the S 2p 3/2 :2p 1/2 doublet overlap commonly reported in nickel sulfides 29 is also found in the bare (MoS 2 ) 300 nanoclusters. However, the upward shift of the Ni 2p 3/2 component to binding energies similar to those of NiO species after air exposure makes the presence of a nickel sulfide phase unlikely.…”

Hierarchical Nanostructures: Design for Sustainable Water Splitting

“…[27,148,149] It is found that the potentiodynamic deposition mode can facilitate the formation of CoS compounds as compared with the conventional chronoamperometric method, which can be attributed to the more efficient formation of Co(II)-TU complexes under the potentiodynamic condition. [142] Despite, it is also possible to achieve well-ordered nanoarrays under chronoamperometric conditions by changing the electrolyte constitutions.…”

Hybrid bioinorganic approach to solar-to-chemical conversion

“…After demonstrating CO 2 -to-CH 4 conversion by M. barkeri during in situ electrolysis using a platinum HER cathode, we sought to replace the precious metal catalyst with an earth-abundant alternative. Several HER catalysts containing only first-row transition metals have been recently reported (57)(58)(59)(60); among these examples, metal chalcogenides have featured prominently (61)(62)(63)(64)(65)(66)(67). In addition to low overpotential and long-term stability, another requirement for a catalyst in a biomaterials hybrid system is that it must operate in aqueous media within a biologically relevant pH range (pH [5][6][7][8] and be nontoxic to the organism.…”