Nickel phosphide (Ni 2 P) has been widely explored toward hydrogen evolution reaction (HER) for desirable durability and high performance. Tuning the electronic structures and morphologies of Ni 2 P plays a pivotal role in the improvement of HER performance. In this work, three Ni 2 P catalysts were fabricated by different strategies and their HER properties were compared. It was found that the bicontinuous porous structured Ni 2 P on Ni foam (Ni 2 P /NFÀ EHP) prepared using coupled electroless nickel-phosphorus (NiÀ P) plating, hydrothermal synthesis and low temperature phosphorization techniques, exhibits the best catalytic activity and a wide pH adaptability. The overpotential at 10 mA cm À 2 and Tafel slope are 78 mV and 33 mV dec À 1 in 0.5 M H 2 SO 4 , those in 1 M PBS are 125 mV and 93 mV dec À 1 , and 101 mV and 76 mV dec À 1 in 1 M KOH. Additionally, the Ni 2 P/NFÀ EHP-catalyzed HER process is also applicable for nitrate reduction with a remarkable removal efficiency of 92.6 %. This catalyst also exhibits a desirable durability both in HER and nitrate reduction. This work offers an efficient strategy to exploit compatible pH-universal HER catalysts, explores the engineering application of HER process in nitrate reduction.

No abstract

No abstract

No abstract

Abstract:The hydrogen evolution reaction (HER) property of molybdenum disulfide (MoS 2 ) is undesirable because of the insufficient active edge sites and the poor conductivity. To enhance HER performance of MoS 2 , nickel phosphide (Ni 2 P) was combined with this catalyst and three MoS 2 /Ni 2 P hybrids (38 wt % Ni 2 P addition for MoS 2 /Ni 2 P-38, 50 wt % Ni 2 P addition for MoS 2 /Ni 2 P-50, and 58 wt % Ni 2 P addition for MoS 2 /Ni 2 P-58) were fabricated via a hydrothermal synthesis process. Morphologies, crystallinities, chemical components, specific surface areas, and HER properties of the fabricated MoS 2 /Ni 2 P samples in an alkaline electrolyte were characterized and tested. In addition, the insight into the HER properties of as-prepared catalysts were revealed by the density functional theory (DFT) calculation. Additionally, the stabilities of pure MoS 2 , Ni 2 P, and MoS 2 /Ni 2 P-50 samples were evaluated. The results show that the addition of Ni 2 P can enhance the HER property of the MoS 2 catalyst. Although HER properties of the above-mentioned three MoS 2 /Ni 2 P hybrids are inferior to that of pure Ni 2 P, they are much higher than that of MoS 2 . Among as-prepared three hybrids, MoS 2 /Ni 2 P-50 exhibits the best HER performance, which may be due to its uniform morphology, large specific surface area, and excellent stability. The MoS 2 /Ni 2 P-50 hybrid shows a high cathodic current density (70 mA/cm 2 at −0.48 V), small Tafel slope (~58 mV/decade), and a low charge transfer resistance (0.83 kΩ·cm 2 ).