Photocatalytic and electrocatalytic hydrogen production promoted by Nd/La substituted cobalt–nickel magnetic nanomaterials

Abstract

The current work concentrates on the design of Nd/La doped Co0.7Ni0.3Fe2O4 nanocatalysts for the green, clean, and sustainable generation of hydrogen through overall photocatalytic and electrocatalytic water splitting routes using sol-gel auto-combustion route. The spinel symmetry with a Fd3m geometry and cubic polycrystalline nature was observed for the developed catalysts. Spherical formed agglomerated nanoparticles having average grain size of 127.10 and 120.08 nm was confirmed for the produced Co0.7Ni0.3Fe2O4 and Co0.7Ni0.3Nd0.02La0.02Fe1.96O4 catalysts through the FESEM results. Maximum saturation magnetization (Ms) of 64.81 emu/g and coercivity (Hc) of 1234.54 Oe were attained by undoped Co0.7Ni0.3Fe2O4 catalyst. This shows the superior magnetic behaviour of our prepared catalysts, for magnetic recording applications. The estimation of photocatalytic hydrogen production for the prepared photo nanocatalysts was conducted under ambient conditions, with an irradiation from a UV-visible light having wavelength range of 200–2400 nm. The prepared Co0.7Ni0.3Nd0.03La0.03Fe1.94O4 photocatalyst shows the maximum photocatalytic activity of 12.57 mmol gcat−1. Also, the photocatalytic hydrogen evolution, repeatability, and stability of all the prepared catalysts were analyzed at three successive cycles. The third cycle showed a little drop in photocatalytic hydrogen evolution to 11.26 mmol gcat−1 as compared to the first cycle. On the other hand, the electrocatalytic activity of produced electrocatalysts were determined towards the electrocatalytic HER via a three-electrode system in 0.5 M H2SO4 electrolyte. The produced Co0.7Ni0.3Nd0.03La0.03Fe1.94O4 nanocatalyst shows excellent electrocatalytic HER activity as compared to other samples. Hence, with photocatalytic/electrocatalytic water splitting traits, the prepared nanocatalysts are highly efficient and suitable for the production of clean and green hydrogen energy sources.