Self-Templated Sputtering Synthesis of III-Nitride Nanowire Array for Solar Water Splitting

Solar water splitting using III-nitride materials holds promise for green hydrogen production; yet, the conventional process for growing III-nitrides, e.g., molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) often incurs relatively high cost. This study presents a cost-effective alternative using magnetron sputtering epitaxy (MSE) to fabricate Mg-doped InGaN nanowires (Mg/MSE-InGaN NWs). Leveraging a unique self-templated growth pattern where metal-polar InGaN forms nanowires and polycrystalline InGaN fills the gaps, selective chemical etching with KOH and HNO₃ exposes the nanowires. The optimized five-step workflow─sputtering, base etching, acid cleaning, magnesium doping, and annealing─achieves a solar-to-hydrogen (STH) efficiency of 0.47% with 120 h of stability, improving significantly from an initial 0.03% via sputter deposition. This scalable, economical approach offers a viable alternative to MBE, enabling the large-scale manufacturing of III-nitride photocatalytic devices for sustainable hydrogen production.