Engineering Cu ₂ O Growth on Titanium Substrate via an MXene Interfacial Layer for Enhanced Photoelectrochemical Performance

Abstract Earth‐abundant and low‐cost materials are desirable for large‐scale solar hydrogen generation. In this outlook, cuprous oxide (Cu 2 O) has significant potential for photoelectrochemical (PEC) water splitting. Thin film growth patterns and high substrate conductivity are a cooperative approach for durable PEC response of Cu 2 O. Herein, we report the improved PEC performance and stability of Cu 2 O thin films electrodeposited on Ti‐coated FTO substrates, with further enhancement achieved through an alternative growth pattern and a corrosion‐protective MXene layer. The alternative growth pattern suppresses Cu 2 O photocorrosion by introducing spatially segregated nanoparticle domains. Upon integration with MXene, the Ti/Cu 2 O/MXene photocathode architecture achieves a significantly enhanced photocurrent (−2.4 mA cm −2 ) at −0.9 V versus Ag/AgCl/Cl − and prolonged stability (6.5 h) owing to improved charge separation and interfacial conductivity. Electrochemical impedance spectroscopy (EIS) analyses confirm the favorable band bending, reduced charge transfer resistance, and faster interfacial kinetics for Ti/Cu 2 O/MXene. Together, these modifications address the longstanding challenges of photo‐corrosion and poor stability in Cu 2 O‐based systems, offering a scalable and cost‐effective route for efficient solar‐driven hydrogen production.