Anchoring metalloporphyrin nanobelts on MXene nanosheets for efficient photocatalytic CO2 reduction

Metalloporphyrins featuring structurally tunable aromatic macrocycles and versatile metal coordination sites are widely recognized as promising molecular catalysts for photocatalytic carbon dioxide reduction. However, their catalytic performances are constrained by rapid recombination of photogenerated charge carriers, insufficient charge transfer efficiency, and structural instability caused by molecular aggregation. Anchoring metalloporphyrins onto conductive substrates, in particular ultrathin two-dimensional (2D) nanostructures, can effectively accelerate interfacial charge transport efficiency, thereby improving photocatalytic activity toward CO₂ reduction. In this work, a novel 2D/2D heterojunction was designed and synthesized, which can serve as a highly efficient molecular catalyst for visible-light-driven CO₂ reduction. The abundant Co centers and N-sites in the assembled cobalt-coordinated porphyrin nanobelts can greatly enhance the adsorption and conversion of CO₂. Meanwhile, the presence of few-layer Ti₃C₂ MXene nanosheets enables the accelerated interfacial charge transport from photoexcited metalloporphyrin to Ti₃C₂ MXene. Rapid electron transfer is verified by Kelvin probe force microscopy (KPFM), in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and irradiated X-ray photonelectron spectroscopy (XPS). As expected, compared to pristine porphyrin, the metalloporphyrin/Ti₃C₂ MXene heterojunction shows a 12.5-fold increase in the photocatalytic activity for CO₂ reduction to CO.