Engineering the work function and interlayer spacing of MXene via the intercalation process for efficient photoelectrochemical water splitting of CuWO4.

In recent years, copper tungsten oxide (CuWO 4) has attracted increasing attention as a highly potential candidate for photoelectrochemical (PEC) water splitting, primarily because of its suitable bandgap, which enables efficient light absorption. However, challenges such as high charge recombination and poor bulk transport have resulted in low PEC performance. To address this, MXene, a novel member of two-dimensional (2D) material, was used to mitigate charge recombination by serving as a hole-transporting layer (HTL) deposited onto a CuWO 4 /FTO substrate. In this study, MXene was fabricated by interactions with different solvents, including tetramethyl ammonium hydroxide (TMAOH), hydrazine (N 2 H 4), and potassium hydroxide (KOH). The work function of MXene and interlayer spacing were adjusted via the intercalation process with various intercalant agents which changes the surface functional groups of MXene to modify the work function and increase the surface area. In addition, the generation of Schottky contact at the CuWO 4 /MXene interface could improve the charge transfer and decrease the charge recombination. The photoelectrodes synthesized in this study were thoroughly characterized using various analytical techniques, including linear sweep voltammetry, high-resolution transmission electron microscopy, electrochemical impedance spectroscopy, and ultraviolet spectroscopy. The results showed a notable improvement in the photoelectrochemical (PEC) performance of 0.35 mA/cm2 of the FTO/CuWO 4 /TMAOH-MXene/Co-Pi photoanode. The synergistic combination of CuWO 4 and MXene facilitated efficient charge transfer from CuWO 4 to the intercalated MXene and reduced electron-hole recombination. The findings suggest that MXene-modified CuWO 4 photoelectrodes hold great potential for efficient hydrogen production, thereby advancing the development of sustainable energy technology. [Display omitted] • The interlayer spacing and work function of MXene were adjusted by the intercalation agents. • The design of CuWO 4 /TMAOH-MXene/Co-Pi photoelectrode exhibited an outstanding PEC performance. • MXene acted as a hole-transporting layer and enhanced the stability of CuWO 4 photoelectrode. [ABSTRACT FROM AUTHOR]