Hybrid Microwave Annealing for Fabrication of More Efficient Semiconductor Photoanodes for Solar Water Splitting

Hybrid microwave annealing (HMA) is proposed as an alternative to conventional thermal annealing (CTA) in a furnace to fabricate efficient semiconductor photoelectrodes for solar water splitting. Thus, the effects of HMA are investigated in comparison with CTA using spinel zinc ferrite as an example. The ZnFe₂O₄ photoanodes fabricated by HMA with a graphite susceptor provide less defective surface, better structural ordering and smaller feature size than photoanodes prepared by CTA. Besides, HMA does not impair conductivity of the F:SnO₂ glass substrate. All these positive factors of HMA leads to ∼4 times higher photocurrents at 1.23 V_RHE and lowered onset potential by ∼100 mV under 1 sun irradiation of an optimized ZnFe₂O₄ photoanode relative to that fabricated by CTA. The HMA could be an effective generic method to fabricate efficient photoelectrodes based on refractory semiconductors replacing incumbent CTA.