National Natural Science Foundation of China.

Because CO2 is the main greenhouse gas, its capture and catalytic conversion are thought to be significant issues to be solved at the current time. Given the thermodynamically stable and inert nature of CO2, it is highly desirable to develop advanced catalysts to facilitate the transformation of CO2 to other high-value-added chemicals under mild conditions. Within this regard, porous organic polymers (POPs), featuring large surface areas, high thermal stabilities, diverse building blocks, and tunable porous structures, are an ideal platform for the construction of heterogeneous catalysts for CO2 conversion. Incorporating active sites that are capable of activating CO2 and/or substrates into the frameworks of POPs can facilitate CO2 conversion. In this Review, the most recent advances in the design and synthesis of POP-based heterogeneous catalysts for the conversion of CO2 are summarized. We mainly focus on the synthetic strategies researchers have used for incorporating active sites into POP frameworks to prepare heterogeneous catalysts for CO2 conversion, including N-doping, metalation, and ionic functionalization. Problems remaining to be addressed in this field are analyzed, and future directions are outlined.

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A hierarchical polyaniline-lignin (PANI-EHL) composite was facilely prepared from aniline and enzymatic hydrolysis lignin in an aqueous solution of ammonia. The morphology, FTIR, UV-vis spectra, thermogravimetric analysis, and wide-angle X-ray diffraction analyses of the composite were systematically investigated. Furthermore, the sorption property of the PANI-EHL composite for silver ions in aqueous solution was studied via a static sorption technique. The result demonstrated that the PANI-EHL composite possessed a strongly reactive sorption characteristic for silver ions. Serrated silver threads with length up to 10 mm were obtained by using the PANI-EHL composite as a low-cost adsorbent. Moreover, the role of EHL and polyaniline in the PANI-EHL composite for silver ions sorption was investigated. The investigation indicated that the EHL unit could play a vital role in the chelation of silver ions, whereas the polyaniline unit played a leading role in redox sorption.

Hydrogen sulfide (H2S) is highly toxic and corrosive, and its selective removal from fuel and flue gases is of significance. It is a challenge to develop a dual-role material for efficient H2S capture as well as selective H2S oxidation. In the present work, we designed a class of nitrogen-decorated ordered mesoporous carbon spheres (denoted herein as N-OMCS-T, where T stands for carbonization temperature) for such an end. The N-OMCS-T with ordered mesopores are large in BET surface area (1201–1500 m2/g), and enriched with nitrogen sites of pyridinic and pyrrolic nature, and exhibit strong interaction with H2S as verified in DFT calculations. With large BET surface areas, ordered mesopores, and abundant nitrogen sites, the N-OMCS-T materials show extraordinary efficacy for the capture of H2S: H2S capacities are up to 13.4 mmol/g (0 °C, 1 bar), and the Ideal Adsorption Solution Theory selectivity in cases of H2S/​CO2, H2S/​CH4, and H2S/​N2 is 2.1–8.5, 11.0–25.5, and 30.4–81.7, respectively, much higher than those of porous materials such as activated carbon, OMCS, Zeolite A, UiO-66, and SBA-15. Moreover, N-OMCS-T could act as efficient and long-lived metal-free catalysts for selective oxidation of the captured H2S to sulfur under mild conditions.