Nickel@Nitrogen‐Doped Carbon@MoS₂ Nanosheets: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

Abstract

Developing cheap, abundant, and easily available electrocatalysts to drive the hydrogen evolution reaction (HER) at small overpotentials is an urgent demand of hydrogen production from water splitting. Molybdenum disulfide (MoS2) based composites have emerged as competitive electrocatalysts for HER in recent years. Herein, nickel@nitrogen‐doped carbon@MoS2 nanosheets (Ni@NC@MoS2) hybrid sub‐microspheres are presented as HER catalyst. MoS2 nanosheets with expanded interlayer spacings are vertically grown on nickel@nitrogen‐doped carbon (Ni@NC) substrate to form Ni@NC@MoS2 hierarchical sub‐microspheres by a simple hydrothermal process. The formed Ni@NC@MoS2 composites display excellent electrocatalytic activity for HER with an onset overpotential of 18 mV, a low overpotential of 82 mV at 10 mA cm−2, a small Tafel slope of 47.5 mV dec−1, and high durability in 0.5 H2SO4 solution. The outstanding HER performance of the Ni@NC@MoS2 catalyst can be ascribed to the synergistic effect of dense catalytic sites on MoS2 nanosheets with exposed edges and expanded interlayer spacings, and the rapid electron transfer from Ni@NC substrate to MoS2 nanosheets. The excellent Ni@NC@MoS2 electrocatalyst promises potential application in practical hydrogen production, and the strategy reported here can also be extended to grow MoS2 on other nitrogen‐doped carbon encapsulated metal species for various applications.

Core‐Shell Structured CoP@MoS2 Electrocatalysts for Enhanced Hydrogen Evolution Reaction

“…The diffraction patterns of CoCo‐PBA matched with the cubic Co 3 [Co(CN) 6 ] 2 (JCPDS 77‐1161) (Figure a). Overall, the diffraction patterns (Figure b) of as‐prepared MoS 2 are similar to those observed in previous work . The poor crystallinity might be caused by the hydro‐carbonization of glucose as reducing agent during the preparation process, which greatly inhibited the growth of MoS 2 crystal, especially in the (002) planes .…”

Engineering Ultrathin MoS2 Nanosheets on CoxP/Nitrogen‐Doped Carbon Nanocubes for Efficient Hydrogen Evolution

“…Two characteristic peaks at around 33°and 57°for bare MoS 2 can be indexed to the (100) and (110) crystal planes of hexagonal 2H-MoS 2 (JCPDS 37-1492), respectively (Figure 2a). [15][16][17] The peak at ∼ 8.9°is assigned to the (002) planes compared to the standard 14.4°for 2H-MoS 2 . The shift of characteristic peak indexed to (002) planes results in the increase of MoS 2 interlayer spacing from the standard 0.62 nm to 0.99 nm, which accelerates the transport and diffusion of H + during the catalytic reaction.…”

Doping‐Assisted Phase Changing Effect on MoS2 Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

“…[20,22,24,27,38,32] It may be due to the improved in-plane electrical conductivity and carrier concentration of MoS 2 after nitrogen doping as observed in earlier cases for the nitrogen-manganese co-doped MoS 2 and nick-el@N-doped carbon@MoS 2 systems. [38,40] Therefore, the HER activity enhancement can be related to the N dopants in the MoS 2 crystal structure. Moreover, the Tafel plots were derived to understand the quantitative kinetics and mechanistic pathway of the HER process in acidic medium as shown in Figure 6b.…”