APTES‐Mediated Ti‐Squarate MOF/ n ‐GaN Nanowire Photoanodes for Efficient Photoelectrochemical Water Splitting
Jeong‐Kyun Oh, Sergio Carrasco, Sooyeon Ra, Seok‐Ho Seo, Chandran Bagavath, Sung‐Un Kim, Min‐Seok Lee, Jong‐Su Kim, Miriam Vos‐Gracia, Dan Na, Kyung‐Hwan Jin, Sangmin An, Dong Ick Son, Cheul‐Ro Lee, Patricia Horcajada, Yong‐Ho RaABSTRACT
While solar‐driven photoelectrochemical (PEC) water splitting offers a promising route for sustainable hydrogen production, sluggish interfacial charge transfer and long‐term instability remain critical bottlenecks. To address these limitations, a chemically integrated Ti‐squarate metal–organic framework (IEF‐11)/ n ‐GaN nanowire (NW) hybrid photoanode is designed via a (3‐aminopropyl) triethoxysilane (APTES) interlayer for efficient PEC water splitting. Density functional theory (DFT) calculations support energetically favorable interfacial bonding and the associated charge redistribution across the APTES‐mediated interface, highlighting the dual role of APTES in chemical anchoring and interfacial electronic modulation. This interfacial modification is accompanied by a reduced work function and a cathodic shift in the apparent flat‐band potential. Consequently, the hybrid photoanode demonstrates accelerated charge‐transfer kinetics, featuring reduced charge‐transfer resistance and a 10.4‐fold enhancement in applied‐bias photon‐to‐current efficiency (ABPE) compared to pristine NWs. Furthermore, this chemical anchoring supports the retention of principal structural and chemical features after 100 h of continuous operation, thereby promoting durable solar‐driven hydrogen production.