Self-assembled CNT/Ni0.85Se-SnO2 networks as highly efficient and stable electrocatalyst for hydrogen evolution reaction

For the first time, a novel porous and conductive Ni0.85Se-based electrocatalyst, CNT/Ni0.85Se-SnO2 networks (CNSN), has been synthesized utilizing a facile solvothermal method. The CNSN exhibit much better hydrogen evolution reaction (HER) performance than bare Ni0.85Se-SnO2 nanoparticles (NSP) and bare Ni0.85Se, with ultra-low Tafel slope of 33.2 mV dec−1, which is comparable to that of commercial Pt/C electrocatalysts, a large cathode current density of 28.4 mA cm−2 (at ∼ −270 mV vs RHE), which is over 4 and 10 times larger than those of NSP (7.1 mA cm−2), and bare Ni0.85Se (2.7 mA cm−2), respectively. It also shows outstanding electrocatalytic stability even after 1500 CV cycles. The superior HER performances of CNSN can be attributed to its well-designed unique nanoarchitecture with high conductivity and rich porosity. Ni0.85Se-SnO2 nanoparticles are anchored on the porous networks constructed with highly conductive CNT, and adjacent Ni0.85Se-SnO2 nanoparticles are tightly connected to each other. As a result, it can not only guarantee strong reactive activity and abundant active sites due to its large specific surface area and rough surface, but also facilitate the charge transfer, resulting in the enhancement of electrocatalytic activity and stability. This work provides a rational structural design and a low-cost, facile synthesis method of transition-metal chalcogenide based electrocatalysts with good stability and high efficiency for hydrogen evolution reaction.