Green hydrogen generation from seawater based on the plasmonic activation induced by Ti3C2 MXene in oxygen-deficient CuO1-X -poly(N-methylpyrrole) photocathodes.

The development of efficient and low-cost photocathodes capable of directly utilizing seawater as an electrolyte is essential for sustainable hydrogen production. Here, we report the fabrication of a CuO1-X -poly(N-methylpyrrole) (PNMP) nanocomposite exhibiting a crystallite size of approximately 10 nm and an optical bandgap of 1.92 eV, enabling broad-spectrum light harvesting. The nanocomposite was deposited onto a poly(1H-pyrrole) (P1HP) interlayer to construct a CuO1-X -PNMP/P1HP photocathode, followed by the incorporation of Ti3C2 MXene to produce a Ti3C2/CuO1-X -PNMP/P1HP heterostructured photocathode. The combination of oxygen-deficient CuO1-X domains, conductive polymer networks, and the metallic Ti3C2 framework promotes photon capture, accelerates charge-carrier transport, and suppresses interfacial recombination. Consequently, the photocurrent density increased from -0.05 mA cm-2 for CuO1-X -PNMP/P1HP to -0.13 mA cm-2 following Ti3C2 integration. The Ti3C2/CuO1-X -PNMP/P1HP photocathode achieved a hydrogen evolution rate corresponding to approximately 6 µmol h-1 cm-2 in an equivalent seawater electrolyte. The enhanced performance originates from the synergistic interaction between the MXene conductive pathways and the defect-engineered CuO1-X semiconductor matrix, which collectively facilitate efficient photoinduced charge separation and transport. These findings demonstrate a promising strategy for the development of scalable and economically viable photocathodes for direct solar-driven hydrogen generation from seawater.