CO2 hydrogenation to methanol, as a green CO2 utilization technology, is one of key method to mitigate global warming. In this study, defect engineering of UiO-66 was systematically investigated by controlling the density and ratio of missing-linker defect (MLD) and missing-cluster defect (MCD) via modulator and post-synthetic exchange (PSE) treatment. The catalytic performance in CO2 hydrogenation to methanol was significantly enhanced via introducing defects into UiO-66, which can effectively modulate the electronic structure and increase the density of active sites. Among the synthesized catalysts, the catalytic performance can be effectively regulated by tuning the quantities of MLD and MCD, and Cu/UiO-66-18T with a moderate number of defects achieved the highest activity, with a CO2 conversion of 12.75% and methanol selectivity of 74.41%. Density functional theory (DFT) calculations revealed that MCD-rich UiO-66 promoted the formation of more Cu-O-Zr interfacial sites, which strengthened CO2 and H2 adsorption compared to MLD-rich UiO-66. Furthermore, the rate-determining step for both MCD-rich and MLD-rich UiO-66 was identified as HCOO* → H2COO*, with MCD-rich UiO-66 exhibiting a lower energy barrier than UiO-66-MLD (1.36 vs 1.41 eV). These results highlight defect engineering, particularly MCD incorporation, as an effective strategy for designing high-performance UiO-66-based catalysts for CO2-to-methanol conversion.

This chapter explores the innovative integration of methanol reforming and heat recovery technologies for sustainable hydrogen production, building on the techno-economic and multi-objective optimization framework presented in the author’s prior research. The focus is on converting methanol-to-hydrogen efficiently while maximizing energy utilization through cascading heat recovery systems. The chapter highlights the role of proton-exchange membrane fuel cells in enhancing system performance and reducing carbon emissions. By leveraging advanced optimization techniques, the proposed system demonstrates significant improvements in energy efficiency and cost-effectiveness, offering a viable pathway for decarbonizing energy systems. The discussion also addresses the challenges and opportunities in scaling up methanol-to-hydrogen technologies, emphasizing their potential to contribute to a sustainable energy future. This work aligns with global efforts to innovate methanol utilization and transition toward cleaner energy solutions.