An S-scheme heterointerface-engineered high-performance ternary NiAl-LDH@TiO2/Ti3C2 MXene photocatalytic system for solar-powered CO2 reduction to produce energy-rich fuels

While there is much potential for photocatalytic CO2 reduction, poor light absorption and high recombination rates of photogenerated charges limit its effectiveness. To address these challenges, we systematically developed a heterointerface-engineered ternary hybrid photocatalyst comprising NiAl-layered double hydroxide (LDH), titanium dioxide (TiO2), and titanium carbide (Ti3C2) MXene via an in situ growth approach. As a result of the unique combination of these three components, the synthesized ternary NiAl-LDH@TiO2/Ti3C2 photocatalyst demonstrated broad light absorption spanning across the ultraviolet, visible, and near-infrared regions, as well as elevated CO2 adsorption capacity. In situ-irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses provided compelling evidence for an unconventional S-scheme charge transfer mechanism in the ternary system that effectively separates the charges and suppresses recombination, allowing NiAl-LDH to maintain its strong reducing capacity and TiO2 to maintain its robust oxidizing capacity. Utilizing the complementary and synergistic properties of these three components (NiAl-LDH, TiO2, and Ti3C2), an optimized ternary NiAl-LDH@TiO2/Ti3C2 photocatalyst with 30 wt% Ti3C2 exhibited extraordinary solar-driven CO2 reduction performance with a remarkable 99 % CO selectivity against competitive H2 production and a high apparent quantum yield of 0.81 at 365 nm. Additionally, the ternary photocatalyst exhibited excellent stability, maintaining its performance capacity over multiple CO2 reduction cycles. This work provides a fresh perspective on designing and creating efficient ternary S-scheme photocatalytic systems for solar-driven CO2 reduction and highlights the potential for energy-rich fuel production.