Rapid thermal processing of photoanodes for solar water splitting: status, challenges and opportunities

Rapid thermal processing (RTP) is gaining attention as an efficient alternative to conventional annealing of materials for photoelectrochemical (PEC) water splitting. By delivering ultrafast heating and precise temperature control, RTP introduces non-equilibrium conditions that enable metastable phase formation, defect engineering, and interfacial control, while preserving transparent conductive oxides (TCOs) essential for PEC architectures. These advantages improve crystallinity, activate dopants, and enhance interfacial quality without the drawbacks of prolonged furnace treatments. Recent studies report two- to fourfold increases in photocurrent density and negative onset potential shifts up to 300 mV for RTP-treated photoanodes, highlighting RTP's potential to accelerate PEC performance toward industrial benchmarks. Despite these advantages, RTP remains underutilized in PEC research, with challenges in process optimization, atmosphere control, and scalability still unresolved. This review summarizes current progress on RTP for several oxide photoanodes, compares its performance with that of conventional annealing processes, and discusses mechanistic insights. Future directions include hybrid thermal strategies, real-time diagnostics, and data-driven design to enable scalable PEC device manufacturing and sustainable solar hydrogen production.