Carbon dioxide (CO₂) electrolysis is a promising route to utilise captured CO₂ as a building block to produce valuable feedstocks and fuels such as carbon monoxide and ethylene. Very recently, CO₂ electrolysis has been proposed as an alternative process to replace the amine recovery unit of the commercially available amine-based CO₂ capture process. This process would replace the most energy-intensive unit operation in amine scrubbing while providing a route for CO₂ conversion. The key enabler for such process integration is to develop an efficient integrated electrolyser that can convert CO₂ and recover the amine simultaneously. Herein, this review provides an overview of the fundamentals and recent progress in advancing integrated CO₂ conversion in amine-based capture media. This review first discusses the mechanisms for both CO₂ absorption in the capture medium and electrochemical conversion of the absorbed CO₂. We then summarise recent advances in improving the efficiency of integrated electrolysis via innovating electrodes, tailoring the local reaction environment, optimising operation conditions (e.g., temperatures and pressures), and modifying cell configurations. This review is concluded with future research directions for understanding and developing integrated CO₂ electrolysers.

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Gas separation performance of mixed matrix membrane heavily depends on the pore structure of the nanofillers. Metal-organic frameworks (MOFs) are promising platform materials for constructing molecular-selective pores for specific applications. In this work, deliberately-selected polymers with CO₂ affinity (PVAm, Pebax and PEI) are employed as pore regulators to manipulate the pore chemistry and size of MOF UiO-66 nanoparticles and consequently control gas transport rate of CO₂ and N₂ molecules. The branched polymer (polyethyleneimine (PEI)) grafted UiO-66, denoted as UKI, is beneficial to enhancing the membrane selectivity. The UKI doped Pebax/mPSf membranes exhibit CO₂/N₂ selectivity up to 278, 6.5 times of the bare Pebax/mPSf membranes. Meanwhile, the CO₂ permeance is boosted from around 690 to 1120 GPU (1 GPU = 10⁻⁶ cm³ (STP)·cm⁻²·s⁻¹·cmHg⁻¹ = 3.35 × 10⁻¹⁰ mol m⁻² s⁻¹·Pa⁻¹). The block copolymer (poly(ether block amide) (Pebax)) grafted UiO-66, denoted as UKX, is conducive to increasing the membrane permeance. The UKX doped Pebax/mPSf membranes exhibited CO₂ permeance up to 1683 GPU, 2.45 times of the bare Pebax/mPSf membranes. Meanwhile, CO₂/N₂ selectivity increased from around 42 to 146. Additionally, excellent pressure-resistant property and outstanding stability are observed under simulated flue gas.

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Membrane-based separation processes can improve separation efficiency and reduce the environmental hazards and energy costs of traditional separation processes. Mixed matrix membranes (MMMs) with broad development prospects are frequently restricted by interfacial incompatibility and the blockage of gas transport channels in the filler matrix. Here, we report a new type of high-valence metal-induced microporous polymer (HMMP-1) filler, with a high density of free amine groups, and having excellent alkaline stability. The HMMP-1 nanoparticles were incorporated into polyvinylamine (PVAm) to prepare facilitated transport mixed matrix membranes (MMMs). The resulting HMMP-1 based MMMs maintain their pore aperture structure, which is mainly due to the excellent compatibility between the polymer component in the HMMP-1 and PVAm. Amine-rich nanochannels with appropriate pore size allow rapid CO₂ transport through the filler pores by preferential adsorption monomolecular surface diffusion, leading to high CO₂ permeance and excellent separation performance for CO₂/CH₄, CO₂/N₂ and CO₂/H₂ compared with many other reported membranes. A techno-economic evaluation suggests that the MMM is feasible for carbon capture from post-combustion flue gas.

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Additive manufacturing strives to combine any combination of materials into 3D functional structures and devices, ultimately opening up the possibility of 3D printed machines. It remains difficult to actuate such devices, thus limiting the scope of 3D printed machines to passive devices or necessitating the incorporation of external actuators that are manufactured differently. Here, 3D printed hybrid thermoplast/conducter bilayers are explored, which can be actuated by differential heating caused by externally controllable currents flowing through their conducting faces. The functionality of such actuators is uncovered and it is shown that they allow to 3D print, in one pass, simple flexible robotic structures that propel forward under step-wise applied voltages. Moreover, exploiting the thermoplasticity of the nonconducting plastic parts at elevated temperatures, it is shown that how strong driving leads to irreversible deformations—a form of 4D printing—which also enlarges the range of linear response of the actuators. Finally, it is shown that how to leverage such thermoplastic relaxations to accumulate plastic deformations and obtain very large deformations by alternatively driving both layers of a bilayer; this is called ratcheting. The strategy is scalable and widely applicable, and opens up a new approach to reversible actuation and irreversible 4D printing of arbitrary structures and machines.@en