Engineering surface and morphology of La/WO3 for electrochemical oxygen reduction†
Altering the surface electronic properties of non-precious electrocatalysts via metal incorporation is an effective approach towards enhancing the oxygen reduction performance. Here, we explored the effect of introducing a rare-earth metal (La up to 20 mole%) in WO3 using a novel crystal engineering strategy. Incorporation of La resulted in coalescence of randomly oriented nanoparticles directed towards one-dimensional growth into nanorods, exposing a preferential high catalytic active facet (002) of WO3. Simultaneously, introduction of La induced the formation of oxygen vacancies at the surface, which coincided with increased hydroxyl adsorption. Benefitting from a combined effect of highly active facet and increased density of surface vacancies, 10% La exhibited two times higher current than pure WO3. An improvement of 90 mV in onset potential highlights the prospects of La addition on electrochemical activity of metal oxides.