Different shapes of various nickel structures, including dendrite, particle and film are fabricated by electrodeposition under various conditions. The shape of nickel structures is definitely dependent on the deposition potential, leading to different electrochemical surface area and edge facets. The nickel particle which has a polycrystalline center and edge is obtained at high negative potential. On the other hand, the nickel dendrite deposited by relatively low negative potential exhibits large electrochemical surface area and a particularly active facet for hydrogen evolution reaction (HER) in alkaline water electrolysis. In fact the nickel dendrite shows the highest catalytic activity and stability for HER among the various nickel structures.

We have investigated the release of active sites blocked by bubbles attached on the surface of catalysts during the oxygen evolution reaction (OER) in alkaline water electrolysis, via the modulation of the wetting properties of the four different morphologies of a nickel catalyst.

Proton exchange membrane water electrolysis (PEMWE), the most energy-efficient low-temperature electrolysis method, is promising for converting intermittent renewable energies into stable hydrogen chemical energy. However, the cumulative corrosive environment resulting from the acidic conditions required and the positive half-cell potentials imply that only materials having high intrinsic activity and stability can be used. Herein, we propose catalysts and a corresponding fabrication method that meets these requirements. A 3D dandelion spore-structured self-supporting IrNi electrocatalyst is directly fabricated on a porous transport layer through the adsorbed H-induced co-electrodeposition of a core–shell IrNi–Ir structure. Subsequent dealloying generates a highly porous nanostructured Ir-based framework robust to the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in a wide pH range. Specifically, it exhibited overpotentials of 248 mV (OER) and 15 mV (HER) at ±10 mA cm⁻² in an acidic electrolyte with exceptional stability even after constant operation at 200 mA cm⁻² for 50 h (OER) or 5000 potential cycles (HER). When used as a bifunctional catalyst (0.67 mg cm⁻²) for PEMWE, 6.5 A cm⁻² was obtained at a cell voltage of 2.0 V. The degradation rate was only 1.58 mV h⁻¹ under extremely harsh test conditions of 2 A cm⁻² for 100 h, thus verifying the exceptional stability of a single cell. This is the first report of bifunctional catalysts with such high performance and stability fabricated using a simple method, and this work can aid the commercialization of PEMWE.

The design of polymer electrolyte fuel cell electrocatalysts depends on two equally important fundamental principles: the optimization of electrocatalytic activities as well as the long-term stability under operating conditions (e.g., pH < 1 and E > 0.8 V). Pt-based alloys with transition metals (i.e., Pt–La) address both of these key issues. The oxygen reduction kinetics depends on the alloy composition which, in turn, is related to the d-band center position. The stability of the oxygen reduction reaction is predictable by correlation of the d-band fillings and vacancies of Pt–M (M = Ti, Fe, Zr and La).

The catalytic activity of amorphous Co–P–B catalysts electrodeposited on carbon paper (CP) for the hydrogen evolution reaction (HER) was investigated in aqueous 0.5 M H₂SO₄ electrolyte.