Mono-, bi- and tri-metallic platinum group metal-free electrocatalysts for hydrogen evolution reaction following a facile synthetic route

In this work, platinum group metal-free (PGM-free) electrocatalysts were synthesized, characterized, and tested for hydrogen evolution reaction (HER). These materials were mono-, bi- and trimetallic Ni-based electrocatalysts with the addition of a second or a third transition metal (TM), such as iron and cobalt. TM–phthalocyanine (TMPc) was used as a metal precursor, mixed with a conductive carbon backbone and subjected to pyrolysis under controlled temperature and atmosphere conditions. Two temperatures of pyrolysis (600 °C and 900 °C) were used. The effect of TM loading in the precursors, different pyrolysis temperatures on the surface chemistry and morphology, and electrocatalytic activity towards HER were evaluated. The increase of NiPc in the initial mixture is beneficial to improving the electrocatalytic activity. The addition of a second and a third metal reflects positively on the HER performance. Interestingly, the pyrolysis temperature influences both the formation and growth of the nanoparticles, and this information is supported by high-resolution transmission electron microscopy (HR-TEM) and light synchrotron X-ray absorption spectroscopy (XAS) measurements.