“Lewis Base-Hungry” Amorphous–Crystalline Nickel Borate–Nickel Sulfide Heterostructures by In Situ Structural Engineering as Effective Bifunctional Electrocatalysts toward Overall Water Splitting

Abstract

The development of high-performance, low-cost, and long-lasting electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is urgently needed for effective electrochemical water splitting. In the present study, an engineering process was employed to prepare “Lewis base-hungry” amorphous–crystalline nickel borate–nickel sulfide (Ni3(BO3)2–Ni3S2) heterostructures, which exhibited unprecedentedly high electrocatalytic activity toward both OER and HER in alkaline media. The optimal Ni3(BO3)2–Ni3S2/nickel foam (Ni3(BO3)2–Ni3S2/NF) electrode displayed an ultralow overpotential of only −92 and +217 mV to reach the current density of 10 mA cm–2 for HER and OER, respectively. When the Ni3(BO3)2–Ni3S2/NF electrode was used as both the anode and cathode for overall water splitting, a low cell voltage of 1.49 V was needed to achieve the current density of 10 mA cm–2, which was superior to the performance of most noble metal-free electrocatalysts. Results from density functional theory calculations showed that the Lewis base-hungry sites in the heterostructures effectively enhanced the chemisorption of hydrogen and oxygen intermediates, a critical step in HER and OER electrocatalysis. Results from this study highlight the significance of rational design and engineering of heterostructured materials for the development of high-efficiency electrocatalysts.

Amorphous/Crystalline Heterostructured Nickel Phosphide Nanospheres for Electrocatalytic Water and Methanol Oxidation Reactions

“…In comparison, the phase engineering strategy receives relatively less attention in the nickel phosphide-based materials. During WOR, surface amorphization is often observed, and amorphous/crystalline heterostructures have shown enhanced electrocatalytic activities on hydroxides, sulfides, and borates . However, few studies focus on the correlation between crystallinity and electrochemical catalytic activities for nickel phosphide-based materials.…”

Molten-Salt-Protected Pyrolytic Approach for Fabricating Borate-Modified Cobalt–Iron Spinel Oxide with Robust Oxygen-Evolving Performance

“…Hydrogen production via water electrolysis is regarded as a promising technique for developing clean energy to replace fossil fuels. − Considering the sluggish reaction kinetics of the oxygen evolution reaction (OER), designing earth-abundant OER catalysts with high catalytic activity and satisfied operational stability is of great importance for further improving the overall efficiency of water splitting. − To date, great efforts have been devoted to the exploration of transition metal-based OER catalysts in various structures, including spinel structures, − layered structures, − perovskite structures, − amorphous structures, ,− and so forth. Aiming on improving the OER activity, enriching the active sites (or facilitating the in situ formation of active species via preoxidation reactions) and enhancing the intrinsic activity of the single site are two basic principles .…”

A Trimetallic Cobalt/Iron/Nickel Phytate Catalyst for Overall Water Splitting: Fabrication by Magnetic‐Field‐Assisted Bipolar Electrodeposition

“…Low cost, easy to scale, and high performance catalysts for hydrogen evolution (HER) and oxygen evolution (OER) are essential [2] . Firstly, owing to the uneconomical disadvantage of the noble metal catalysts (Pt/C and RuO 2 ) for overall water splitting, developing the dual‐function transition metal materials such as metal oxides, [3] sulfides, [4] nitride compounds [5] and phosphates composites [6] are very crucial. Additionally, compared with mono‐metal complexes, polymetallic complexes have been proved to show richer faraday redox, higher conductivity and stability due to the optimization of their electronic structure [7] .…”