Performance of hydrogen evolution reaction of R3C ferroelectric ZnSnO3 nanowires

Effect of the Seed Layer on the Growth and Charge Transfer Behavior of Zn2SnO4 Nanorods in Photoelectrochemical Water Splitting

The growth of Zn2SnO4 nanorods on two differently prepared ZnO seed layers is demonstrated using a hydrothermal approach. The ZnO seed layers are prepared using dip-coating and electrodeposition techniques. The grown Zn2SnO4 nanorods are in the cubic phase. However, the different seed layers result in alternation in the diameter of grown Zn2SnO4 nanorods. The photocurrent of Zn2SnO4 nanorods grown on an electrodeposited ZnO seed layer is ∼4.5 times larger than that of Zn2SnO4 grown on a dip-coated ZnO seed layer. The Nyquist plots of Zn2SnO4 nanorods on the electrodeposited ZnO seed layer result in a lower charge transfer resistance (Rct = 37.7 Ω) and a lower bulk resistance (Rbulk = 64 kΩ), improving the charge transport properties. The change in diameter of Zn2SnO4 nanorods significantly alters the charge transfer behavior. The calculated charge injection efficiency did not exhibit a significant change. However, there was a 1.6-fold enhancement observed in the charge separation efficiency for Zn2SnO4 when grown on an electrodeposited seed layer.

Self-supported nickel sulfide derived from nickel foam for hydrogen evolution and oxygen evolution reaction: effect of crystal phase switching

Designing and fabricating economically viable, high active and stable electrocatalysts play an important role for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Crystal phase is the crucial factor that governs the electrochemical property and electrocatalytic reaction pathways. Here, a one-step nickel foam derived sulfidation method was presented to synthesize self-supported NiS₂ and Ni₃S₂. The crystal phase-dependent chemical properties related to electrocatalytic behavior were evaluated by a series of advanced characterization and density functional theory calculations. Overall, the self-supported Ni₃S₂ shows high electrochemical activity towards both HER and OER in alkaline conditions, which afford the current density of 10 mA cm^-2 with overpotentials of 245 mV for OER and 123 mV for HER, respectively. When employed the self-supported Ni₃S₂ as the bifunctional electrocatalysts for overall water splitting, the entire device provides the current density of 10 mA cm^-2 at 1.61 V. These results indicate that the electrocatalytic properties can be exert greater improved by controlling the crystal phase, offering the prospect for advanced materials design and development.