Enhanced photocatalytic hydrogen production over TiO₂-based composites modified with ferroelectric BST, MXenes, and metal co-catalysts

The global rise in energy demand and the continuous increase in atmospheric CO₂ emissions have underscored the urgent need to develop cleaner and more sustainable energy technologies. Among the different strategies under study, photocatalytic hydrogen production is especially attractive, as it enables the conversion of solar energy into a carbon-free fuel. Titanium dioxide (TiO₂) is one of the most widely investigated photocatalysts owing to its stability, low cost, and non-toxicity. However, its practical efficiency remains limited by rapid electron–hole recombination and weak absorption in the visible region. In this work, we synthesized novel TiO₂-based composites modified with ferroelectric BST perovskites (Ba_1-xSr_xTiO₃), conductive MXene (Ti₃C₂T_x), and metallic co-catalysts (Ni/Cu). The samples were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy (PL), and Brunauer–Emmett–Teller (BET) surface area analysis to evaluate their structural, optical, and morphological properties. Photocatalytic tests revealed a clear enhancement in hydrogen photoproduction. While pure TiO₂ generated around 0.5 mmol h^-1 ·g_cat^-1, the best-performing TiO₂/BST/MXene/Cu composite reached values equal to ~60 mmol ·h^-1 ·g_cat^-1. This improvement can be attributed to the synergistic contribution of each component. BST helps to separate charges more efficiently thanks to the internal electric field within its ferroelectric structure, which reduces the chance of electron–hole recombination. At the same time, MXenes act as highly conductive pathways, facilitating efficient electron transfer to the metal co-catalyst sites. As a result, charge recombination is suppressed, leading to a significant increase in hydrogen evolution activity. Overall, the obtained results demonstrate that combining TiO₂ with BST, MXene, and Cu metal co-catalysts is a highly effective strategy for enhancing photocatalytic performance and supports the development of renewable hydrogen technologies.