Despite being a promising and efficient methodology for producing green hydrogen as a novel energy vector, anion exchange membrane water electrolyzers (AEMWEs) have yet to achieve significant commercial success. This is primarily due to the sluggish and complex oxygen evolution reaction (OER) at the anode, which remains the main bottleneck for this technology. To enhance the OER kinetics with minimum overpotentials, scarce and overpriced noble metal-based electrocatalysts are largely utilized, making the AEMWEs practically unaffordable. Recently, amorphous NiFe mixed oxides with variable Ni/Fe ratios have been synthesized using a simple and affordable sol–gel method, successfully enhancing both the OER activity and operational durability in AEMWEs. This work was published in Industrial Chemistry & Materials in March 2025.
AEMWEs are considered one of the most reliable technologies to produce green hydrogen, which is a novel energy vector, paving the way towards a sustainable future with environmental safety by mitigating issues such as global warming and climate change due to the burning of fossil fuels. However, the mass-scale deployment of the AEMWEs is still restricted, stemming from the anode side involving sluggish and complex OER, which is usually dealt with by scarce and overpriced noble metal-based electrocatalysts. Being a reliable substitute for noble metal-based electrocatalysts, Ni-Fe mixed oxides are drawing scientific attention, which is attributed to their higher abundance, low cost, favorable electronic structure, adjustable stoichiometries, and intrinsic electrocatalytic activities. However, a straightforward and affordable sol-gel synthesis pathway for amorphous Ni-Fe mixed oxides tailored for OER applications has been lacking. It is important to note that the synthesis design, stoichiometry, and physicochemical properties of the resulting electrocatalysts critically influence their overall OER performance. Therefore, a comprehensive understanding of these factors in the development of amorphous NiFe mixed oxides through a simple and controllable fabrication method constitutes an important research gap.
Under the leadership of Prof. Carlo Santoro and Prof. Roberto Nisticò, a multidisciplinary team of scientists from various research and academic institutions recently endeavored to synthesize nanostructured amorphous Ni-Fe mixed oxides with varying Ni/Fe ratios. The morphological, structural, and physicochemical characteristics of the complete array of such Ni-Fe oxides with different Ni/Fe ratios were thoroughly analyzed. Moreover, the corresponding electrocatalytic activities towards OER were evaluated as a function of ink formulations and electrocatalyst loading through rotating ring electrode methodology. Hence, the evolved electrocatalysts demonstrated optimal OER performance and excellent durability when configured as an anode in lab-scale AEMWEs. Among the variants, Ni:Fe = 0.75:0.25 oxide exhibited the peak performance, achieving a low overpotential of 291 mV. The same material rationalized the highest current density and remarkable stability over 100 hours in the AEMWE operating at 80 °C. This superior activity was attributed to a higher concentration of Ni³⁺ (NiOOH), a highly active species for the OER, while getting the synergic effects from the amorphous architectures.
Building on this initial success, the research team aims to further enhance the electrocatalytic properties of the developed Ni-Fe oxide-based materials by optimizing their morphology, structural characteristics, and surface chemistry. These improvements are expected to further reduce overpotentials and boost overall OER performance.
The research team includes: Lorenzo Mirizzi, Mohsin Muhyuddin, Carmelo Lo Vecchio, Erminia Mosca, Vincenzo Baglio, Irene Gatto, Enrico Berretti, Alessandro Lavacchi, Valerio CA Ficca, Rosanna Viscardi, Roberto Nisticò and Carlo Santoro. The work was a collaborative effort of the University of Milano-Bicocca (Milan), the CNR-ITAE Consiglio Nazionale Delle Ricerche Institute for Advanced Energy Technologies (Messina), CNR-ICCOM Istituto di Chimica Dei Composti Organo Metallici-Consiglio Nazionale Delle Ricerche (Firenze) and ENEA Casaccia Research Center (Rome), Italy.
Industrial Chemistry & Materials is a peer-reviewed interdisciplinary academic journal published by Royal Society of Chemistry (RSC) with APCs currently waived. ICM publishes significant innovative research and major technological breakthroughs in all aspects of industrial chemistry and materials, especially the important innovation of the low-carbon chemical industry, energy, and functional materials. Check out the latest ICM news on the blog .
