Cher Hon Lau

Reversible light-driven adsorption in framework materials offers a route to energy-efficient separations, yet current mechanisms deliver modest working capacities that constrain practical utility. Here we introduce photo-reversible defect complexation as a design principle for enhancing light-induced working capacities, coupling photoswitch isomerisation to active binding site modulation rather than pore geometry changes alone. We exploit coordinatively unsaturated Zr sites in defective UiO-67 as reversible binding sites, where a grafted spiropyran (SP) photoswitch undergoes UV-induced isomerisation to the zwitterionic merocyanine (MC) form, whose phenolate oxygen coordinates an additional open Zr site, suppressing guest binding availability. Visible light fully reverses this process. This mechanism delivers an 83% enhancement in photo-modulated CO ₂ working capacity, reaching 1.1 mmol g ⁻¹ , nearly double that of the structural analog of P-UiO that does not enable photo-reversible MC-defect switching. Light-controlled metal cation and CO ₂ uptake confirms that binding site availability, rather than pore geometry, drives this switching response. Density functional theory (DFT) simulations and multimodal X-ray photoelectron spectroscopy (XPS) confirm reversible MC-Zr site complexation as the operative mechanism with performance retained across multiple photocycles. These findings establish photo-reversible defect engineering as a robust and broadly applicable principle for light-responsive frameworks with modulable guest adsorption.

Photocatalytic hydrogen peroxide (H ₂ O ₂ ) synthesis from water and oxygen is a promising alternative to the anthraquinone process, but its efficiency depends on charge separation and reactant transport. Herein, we report a side chain strategy to regulate nanochannel microenvironments of hydrazone‐linked covalent organic frameworks (COFs). Four COFs bearing H, OMe, OEt, or OEtOMe groups were prepared using the same benzotrithiophene node and hydrazone‐linked framework. The alkoxy side chains tune pore polarity, accessible porosity, electronic properties, and water and oxygen adsorption. Among them, COF‐Hz‐OEtOMe exhibits the strongest water and oxygen affinity and favorable charge‐separation behavior. It achieves an H ₂ O ₂ production rate of 7240 µmol g ⁻¹ h ⁻¹ at the optimized catalyst loading in pure water and 22910 µmol g ⁻¹ h ⁻¹ with benzyl alcohol. A 1 L reactor using tap water and air accumulates 1.42 mM H ₂ O ₂ after 4 h under natural sunlight. Experiments and theoretical calculations suggest that the conjugated framework promotes charge separation, while the alkoxy‐functionalized nanochannels improve reactant adsorption and oxygen activation. Life cycle assessment (LCA) highlights that natural sunlight and larger‐scale catalyst synthesis can reduce the calculated climate impact. These results demonstrate that pore‐wall side chain engineering provides an effective strategy for regulating charge behavior and reactant transport in porous photocatalysts.

Photocatalytic hydrogen peroxide (H ₂ O ₂ ) synthesis from water and oxygen is a promising alternative to the anthraquinone process, but its efficiency depends on charge separation and reactant transport. Herein, we report a side chain strategy to regulate nanochannel microenvironments of hydrazone‐linked covalent organic frameworks (COFs). Four COFs bearing H, OMe, OEt, or OEtOMe groups were prepared using the same benzotrithiophene node and hydrazone‐linked framework. The alkoxy side chains tune pore polarity, accessible porosity, electronic properties, and water and oxygen adsorption. Among them, COF‐Hz‐OEtOMe exhibits the strongest water and oxygen affinity and favorable charge‐separation behavior. It achieves an H ₂ O ₂ production rate of 7240 µmol g ⁻¹ h ⁻¹ at the optimized catalyst loading in pure water and 22910 µmol g ⁻¹ h ⁻¹ with benzyl alcohol. A 1 L reactor using tap water and air accumulates 1.42 mM H ₂ O ₂ after 4 h under natural sunlight. Experiments and theoretical calculations suggest that the conjugated framework promotes charge separation, while the alkoxy‐functionalized nanochannels improve reactant adsorption and oxygen activation. Life cycle assessment (LCA) highlights that natural sunlight and larger‐scale catalyst synthesis can reduce the calculated climate impact. These results demonstrate that pore‐wall side chain engineering provides an effective strategy for regulating charge behavior and reactant transport in porous photocatalysts.

The efficient conversion of solar energy into chemicals is fundamentally limited by the rapid, random recombination of photogenerated charges and strong exciton binding in semiconductors. We transcend incremental catalyst optimization by introducing a universal molecular design strategy “simultaneous geometric and electronic symmetry breaking” in covalent organic frameworks that intrinsically programs directional charge flow. Our strategy of replacing symmetric benzene units with asymmetric thiophene rings induces cooperative point‐group distortion and asymmetric electron density redistribution, thereby creating a built‐in polarization field that slashes exciton binding energy, extends carrier lifetime by over 300%, and steers reaction selectivity. This leads to a record photocatalytic H ₂ O ₂ production rate from just water and air. Crucially, life‐cycle assessment confirms this pathway reduces environmental impact by an order of magnitude. The generality of this design strategy is further validated across multiple framework systems and enables stable operation in a continuous‐flow photoreactor, demonstrating a robust platform for efficient solar‐to‐chemical energy conversion.

The efficient conversion of solar energy into chemicals is fundamentally limited by the rapid, random recombination of photogenerated charges and strong exciton binding in semiconductors. We transcend incremental catalyst optimization by introducing a universal molecular design strategy “simultaneous geometric and electronic symmetry breaking” in covalent organic frameworks that intrinsically programs directional charge flow. Our strategy of replacing symmetric benzene units with asymmetric thiophene rings induces cooperative point‐group distortion and asymmetric electron density redistribution, thereby creating a built‐in polarization field that slashes exciton binding energy, extends carrier lifetime by over 300%, and steers reaction selectivity. This leads to a record photocatalytic H ₂ O ₂ production rate from just water and air. Crucially, life‐cycle assessment confirms this pathway reduces environmental impact by an order of magnitude. The generality of this design strategy is further validated across multiple framework systems and enables stable operation in a continuous‐flow photoreactor, demonstrating a robust platform for efficient solar‐to‐chemical energy conversion.

Here we present a solvent decision-making pathway for less hazardous and scalable synthesis of TpPa-1 covalent organic framework (COF) underpinned by environmental compatibility (CHEM21 framework), processability (Hansen solubility parameters), and thermodynamic suitability (free energy of solvation). Our analyses suggest that solvents with moderate solvation, such as 1,4-dioxane, propylene carbonate, and diacetin, hinder excessive reaction reversibility and promote crystallite growth. Balancing solvent greenness, compatibility, and thermodynamics, we find that diacetin is optimal for a continuous-flow synthesis. Compared with TpPa-1 COF synthesized in diacetin under batch conditions, the Brunauer–Emmett–Teller surface area of flow-derived TpPa-1 reached 418 m² g^–1, increasing CO₂ uptake by 50% at 298 K. The flow process achieved a 30-fold increase in space-time yield (STY), with excellent reproducibility and an 89% reduction in specific energy consumption. This solvent-thermodynamics-guided approach establishes a physically transparent and sustainable framework for optimizing COF synthesis under continuous-flow conditions.

Liquid-processable metal-organic framework (MOF) glasses well redefine the ideal materials for energy-efficient carbon capture membranes. However, MOF glass membranes still suffer from poor pore connectivity, inadequate porosity and severe pressure vulnerability, hindering the sustainable deployment of membrane technologies in flue gas decarbonization, natural gas valorization, etc. Herein, we report a nature-inspired molecular weaving method to synthesize a de novo pw-MOF (polymer woven MOF) glass family. During melting, the woven polymer protects against lattice deformation while undergoing a nanophase interface segregation (nano-IS) evolution, which effectively regulates the kinetic mass transfer efficiency and thermodynamic polar adsorption effect. The newly synthesized pw-MOF glass membranes contain connected subnanometer penetrating channel networks with high-density polar domains for adsorption along the polymer chains to achieve a recorded performance, exemplified by the CO₂/N₂ and CO₂/CH₄ systems, surpassing the most recent upper bound. Owing to the unique woven reinforced framework, our pw-MOF glass membranes demonstrate an unprecedented pressure tolerance of up to 7.5 atm, which has not been realized by contemporary MOF membranes, which usually malfunction at 1 atm. This nature-inspired weaving design philosophy for synthesizing unconventional materials and constructing exceptional architectures is versatile for cultivating next-generation sustainable materials.

Nanofiltration membranes with confined nanopores are vital for energy-efficient molecular and ionic sieving towards sustainable ecosystems. However, the production of contemporary nanofiltration membranes still relies on hazardous petrochemical-based chemicals, raising serious water contamination concerns and complicating after-usage disposal. This phenomenon contradicts the sustainability of membranes derived from green chemistry principles, emphasizing not only their eco-friendly application but also their preparation and end of life. Here we report the synthesis of a sustainable nanofiltration membrane (SNFM) with superior performance for water treatment and an inherent natural soil degradation mechanism through a safer approach utilizing integrated low-hazard chemicals. Experiments and simulations confirmed that our SNFM can be fabricated in an environmentally friendly manner and decomposed by natural soil microorganisms, contributing to its distinctive eco-friendliness. Notably, the SNFM demonstrated both exceptional water permeance and molecular and ionic sieving capability, outperforming commercial and state-of-the-art membranes. This approach establishes a new paradigm for next-generation water recycling and sustainable chemical processes.

Hypercrosslinked polymers (HCPs) are widely used in ion exchange, water purification, and gas separation. However, HCP synthesis typically requires hazardous halogenated solvents e. g., dichloroethane, dichloromethane and chloroform which are toxic to human health and environment. Herein we hypothesize that the use of halogenated solvents in HCP synthesis can be overcome with deep eutectic solvents (DES) comprising metal halides–FeCl ₃ , ZnCl ₂ that can act as both the solvent hydrogen bond donor and catalyst for polymer crosslinking via Friedel Crafts alkylation. We validated our hypothesis by synthesizing HCPs in DESs via internal and external crosslinking strategies. [ChCl][ZnCl ₂ ] ₂ and [ChCl][FeCl ₃ ] ₂ was more suitable for internal and external hypercrosslinking, respectively. The specific surface areas of HCPs synthesized in DES were 20–60 % lower than those from halogenated solvents, but their CO ₂ /N ₂ selectivities were up to 453 % higher (CO ₂ /N ₂ selectivity of poly‐α,α’‐dichloro‐p‐xylene synthesized in [ChCl][ZnCl ₂ ] ₂ via internal crosslinking reached a value of 105). This was attributed to the narrower pore size distributions of HCPs synthesized in DESs.

Exploiting photo-isomerisation of azobenzene molecules embedded in pores of hypercrosslinked polymers to drive adsorption (upon UV light irradiation) and desorption (visible light irradiation) of CO ₂ to enable low-energy, low-cost carbon capture.