The Effect of Ga Incorporation in TiO₂/SnO₂ Nanoparticle-Decorated Hierarchical ZSM-5 Composite as Precious-Metal-Free Electrocatalysts for Oxygen Electro-Reduction

The slow nature of oxygen electro-reduction has become a major obstacle in fuel cell commercialization. Researchers have recently focused on developing efficient electrocatalysts to address this issue. In this study, we investigated the catalytic activity of electrocatalysts based on metal-incorporated zeolites. We prepared the zeolite socony mobil-5 (ZSM-5) zeolite samples hydrothermally and modified them to introduce mesopores and metal nanoparticles. The metal nanoparticles were supported on the hierarchical zeolite socony mobil-5 (HZSM-5) support materials by ion-exchange process. Surface morphology analysis revealed that the pristine material had a smooth surface which became rough upon post-modification of the material. Hierarchical zeolites showed large surface area and pore volume. The TiSn-loaded-HZSM-5 demonstrated higher catalytic efficiency than other prepared electrocatalysts for ORR. The catalytic efficiency of the synthesized electrocatalysts was in the order TiSn-HZSM-5>GaSn-HZSM-5>TiGaSn-HZSM-5>TiGa-HZSM-5 with the onset potential of 0.86, 0.81, 0.80 and 0.78 V respectively. Catalysis is affected by the size, dispersion and electronic state of metal nanoparticles as observed by the catalytic efficiency of the trimetallic electrocatalysts which have low catalytic activity compared to bimetallic counterparts. Bimetallic hierarchical zeolites based electrocatalysts have great potential in catalysis, but there is still room for improvement.