Controllable Preparation Of Nickel Phosphide Nanoparticles And Their Hydrogen Evolution Behavior

It is widely considered that hydrogen is the promising energy carrier because of its larger storage density,longer storage time and environmentally friendly property.Among all kinds of hydrogen production methods,water electrolysis is a clean,simple and fast way to produce hydrogen in large scale.Unfortunately,the high cost and low energy conversion efficiency are hindering its development.Therefore,finding an inexpensive and abundant catalyst is very inportant which would facilitate the industrialization of hydrogen production.In this paper,nickel phosphide nanoparticles?Ni-P NPs?were selected as the researched hydrogen evolution reaction?HER?catalyst.In order to find out the potential application of Ni-P NPs in water electrolysis,synthesis method and electrchemical properties were disscussed.The main novel points are shown as follows:1.Ni-P NPs with different sizes were prepared by self-catalysed reduction method.The XRD results show that the prepared Ni-P NPs are amorphous,and the TEM diagrams show Ni-P NPs exhibited polydisperse channeled nanosphere morphology.The synthesis method not only can effectively control the particle size of Ni-P NPs,but also has the advantages of low cost and simple process,which making it very suitable for large-scale production.2.The electrochemical tests of Ni-P NPs with different particle size in alkaline conditions show that their HER catalytic performance are all poor without any obvious difference.However,after crystallization of Ni-P NPs,their HER catalytic performance have been largely improved,and crystalline Ni₁₂P₅ has much excellent HER catalytic activity.X-ray diffraction,transmission electron microscopy and X-ray photoelectron spectroscopy reveal that Ni-P bond formed during crystallization,making Ni positively charged and P negatively charged.This charged nature of Ni₁₂P₅ is similar to[NiFe]hydrogenase and its analogous,which make the removal of H₂ less energy-cost.3.In order to investigate the application potential of Ni-P NPs in solid polymer acid electrolysis cell,their HER catalytic performance in 0.5 M H₂SO₄ and 1M NaOH were compared.The electrochemical tests show that they exhibit better HER catalytic performance under acidic conditions than in alkaline conditions,and the Ni₁₂P₅ have the excellent performance under acidic conditions.However,in terms of stability,the stability of Ni₁₂P₅ in alkaline conditions is better than in acidic conditions.4.In order to further explore the application potential of Ni-P nanoparticles in water electrolysis,the oxygen evolution reaction?OER?catalytic performance was also discussed.The electrochemical tests of Ni-P NPs with different crystallinity show their OER catalytic performances are very similar which are not good enough compared with the reported catalytic material.