Organic acid-functionalized transition metal-free layered CaO-based dual-function materials for enhanced integrated CO2 capture and utilization

Transition metal-free CaO-based dual-function materials (DFMs) are promising for integrated CO 2 capture and utilization (ICCU) due to their cost-effectiveness, exceptional CO selectivity (>99 %), and negligible byproducts. Spent DFMs also enable industrial reuse (e.g., cement production), enhancing sustainability. However, their limited CO 2 adsorption capacity and subpar catalytic performance hinder the efficiency of ICCU. We introduce an organic acid functionalization strategy that significantly boosts ICCU performance and elucidates structure-activity relationships between the organic acid type, the structure of the DFMs, and the ICCU performance. Citric acid-functionalized CaO DFMs exhibit superior performance with 13.3 mmol g −1 CO 2 uptake (+31.4 %) and 10.5 mmol g −1 CO yield (+73.4 %). Remarkably, the citric acid-functionalized CaO DFMs exhibit significantly enhanced stability over 100 cycles compared to commercial CaO. These enhancements stem from gases released during post-functionalization calcination and a resulting 100 nm-thick nanosheet morphology, which not only increases surface area and exposes more active sites, thereby improving their accessibility, but also prevents the formation of inert CaCO 3 product layer on the surface of DFMs, allowing CO 2 to react with the internal CaO. Techno-economic analysis confirms a 40 % cost reduction versus conventional materials, establishing a paradigm for efficient, economically viable DFMs for carbon-negative chemical production. • CaO-C nanosheets with a thickness of 100 nm avoid deactivation from an inert CaCO 3 product layer. • Clear structure-activity relationship between organic acids, DFM structures, and ICCU performance is revealed. • CaO-C exhibits superior performance: 13.3 mmol g −1 CO 2 uptake (+31.4 %) and 10.5 mmol g −1 CO yield (+73.4 %). • Compared with CaO-S, the cost of CaO-C has been reduced by 40 %.