Electrocatalytic activity of porous Ni–Fe–Mo–C–LaNi₅ sintered electrodes for hydrogen evolution reaction in alkaline solution

Abstract

The hydrogen evolution reaction (HER) was studied in 6 M KOH solution at temperatures ranging between 303 K and 353 K on a porous Ni-Fe-Mo-C-LaNi 5 electrode. By using steady-state polarization curves and electrochemical impedance spectroscopy (EIS), the surface roughness factor and the intrinsic activities of the porous Ni-Fe-Mo-C-LaNi 5 electrode have been determined. The Tafel slope of the best-performing porous Ni-Fe-Mo-C-LaNi 5 cathode materials is 140 mV dec À1, and the exchange current density is 9.9 Â 10À4 A cm À2 at elevated temperature. The roughness factor is 8600, which was obtained for the HER on studied electrodes in 6 M KOH solution at 323 K temperature using the EIS data and complex nonlinear least square (CNLS) approximation method. These techniques also permitted us to determine the mechanism and kinetics of the HER on the investigated electrode. The overall experimental data indicates that the porous Ni-Fe-Mo-C-LaNi 5 electrode yields electrocatalytic activity in the HER.Nevertheless, when the effect of the surface roughness is taken into consideration, it is demonstrated that alloying Ni with Fe, Mo, C and LaNi 5 results in an increased electrocatalytic activity in the HER when comparing to pure Ni. This is due to an improved intrinsic activity of the material, which is explained on the basis of the synergism among the catalytic properties of Ni and of Fe, Mo, and induced by C embedded into Ni-Fe matrix and Ni-Fe-Mo matrix. LaNi 5 enhances the H adsorption on the electrode surface and mainly plays a role of hydrogen storage for HER.

Role of MIL-53(Fe)/hydrated–dehydrated MOF catalyst for electrochemical hydrogen evolution reaction (HER) in alkaline medium and photocatalysis

“…The electrochemical hydrogen evolution reaction (HER) is one of the main cathodic reactions in electrochemical energy conversion devices. 5 To meet the requirements of a HER, efficient electrocatalysts are imperative owing to the multi electron nature of dihydrogen generation through proton reduction 6 and reduction of over potential (h). In general, electrocatalytic materials are found to the best solution for low production costs and reducing the over potential of a hydrogen evolution reaction (HER).…”

Porous Ni Photocathodes Obtained by Selective Corrosion of Ni-Cu Films: Synthesis and Photoelectrochemical Characterization

“…Moreover, the NiO p-type semiconductor has emerged as the most frequently used material in this field for its low cost, good stability, and suitable band position alignment, for the transfer of photogenerated holes to counter electrode, that is a key efficiency-determining step of PEC water splitting [14][15][16]. In order to increase the catalytic activity of nickel based materials towards the HER, two basic approaches could be adopted, namely the use of multicomponent catalysts and the increase of the real surface area [17]. Ni-based alloys, together with other transition metals or rare earths, have been widely studied and exhibited better catalytic capability than single Ni catalyst, due to synergistic effects of the elements forming the alloy [18,19].…”