Onsite Substitution Synthesis of Ultrathin Ni Nanofilms Loading Ultrafine Pt Nanoparticles for Hydrogen Evolution

Here, the ultrathin Ni nanofilms loading ultrafine Pt nanoparticles (Ni/Pt nanocomposites) were synthesized by a simple substitution method for the electrocatalysis of hydrogen evolution reaction (HER). First, the ultrathin Ni nanofilms were prepared by using NaBH4 to reduce Ni salt. Then the ultrafine Pt nanoparticles attached on the surface of the ultrathin Ni nanofilms through the onsite substitution reaction between PtCl6(2-) and Ni element. X-ray photoelectron spectroscopy (XPS) experiment confirmed that Ni in Ni/Pt nanocomposites exists in the form of Ni(OH)2. Transmission electro microscope (TEM) study showed that the ultrafine Pt nanoparticles were sufficiently dispersed and loaded at Ni ultrathin nanofilms. The obtained Ni/Pt nanocomposites exhibited superior activity of HER and good stability in acidic media. It obtained 10 and 100 mA/cm(2) with overpotential of only 36 and 115 mV, respectively. The stability experiment of 20,000 s gave nearly negligible current decrease. On the one hand, the ultrathin Ni nanofilms help to disperse and form the ultrafine Pt nanoparticles. On the other hand, the ultrathin Ni nanofilms help to load the ultrafine Pt nanoparticles as catalyst support and immobilize both of them onto the electrode surface because of the high surface free energy of ultrathin nanofilm and the leading high adsorption ability. In addition, Ni itself exhibited somewhat electrocatalytic activity of HER, which contributed to the whole HER electrocatalysis of Ni/Pt nanocomposites. The excellent electrocatalysis may lead to the decreased consumption of expensive Pt and open up new opportunities for applications in hydrogen energy.