Light-Induced Structural Dynamic Evolution of Pt Single Atoms for Highly Efficient Photocatalytic CO2 Reduction

Microwave-Assisted Catalytic Upcycling of Plastic Wastes over Heterojunction-Structured Layered Triple Oxides

Chemical upcycling of plastic wastes into valuable chemical feedstocks and simultaneous mitigation of environmental deterioration are fascinating but remain extremely challenging. Herein, we report microwave-assisted valorization of plastic wastes into carbon nanotubes (CNTs) and hydrogen (H2) over heterojunction-structured mixed metal oxides. Specifically, the CoNiFe-based layered triple oxides (LTO) arrayed on Ni-foam (CoNiFe-LTO@foam) were constructed. The special heterojunction of the LTO endows high dielectric loss, facilitating efficient conversion of absorbed microwave energy into thermal energy. Most importantly, the synergistic effect of the multiple transition metal sites boosts the cleavage of carbon chains and dehydrogenation, thereby accelerating the reaction kinetics. As a result, the CoNiFe-LTO@foam achieves an H2 selectivity of ∼95 vol % with the yield of ∼69 mmol · g plastic - 1 for upcycling polyethylene in 25 cycles of measurement. Simultaneously, the CNTs attain a yield of ∼35%, which can be used for aqueous chloride-ion batteries. Additionally, the CoNiFe-LTO@foam enables facile recovery of CNTs and prevents the loss of catalytic sites, facilitating upcycling of various real-world plastic wastes. Our work thus highlights the innovations of an advanced catalytic system for forming a closed loop of plastic C/H and achieving the ultimate goal of a carbon-neutral society.

Aligning Metal Coordination Sites in Metal-Organic Framework-Enabled Metallaphotoredox Catalysis

Construction of catalytic metal centers, the key modules in artificial photosynthetic systems, lies at the heart to explore unpaved reactivity patterns powered by light. Here, we disclose that the amino (-NH₂) and carboxylic (-COO) functionalities, aligned in various visible-light-harvesting metal-organic frameworks (MOFs) (NH₂-UiO-66, (NH₂)₂-UiO-67, and NH₂-MIL-125), provide N/O-ligated Ni featuring different configurations and valence states. Of note, these Ni centers, in situ formed or preimplanted, demonstrated coordination units' spatial arrangement-dependent activity in cross-coupling of aryl halides and various nucleophiles. Our work provides a novel approach to construct and to regulate metal center(s) by MOFs' skeleton defined coordination environments, highlighting exclusive potential in exploring the reactivity pattern of the hosted metals.

A Carbon-Negative Hydrogen Production Strategy: CO2 Selective Capture with H2 Production

We reported a strategy of carbon-negative H₂ production in which CO₂ capture was coupled with H₂ evolution at ambient temperature and pressure. For this purpose, carbonate-type Cu_x Mg_y Fe_z layered double hydroxide (LDH) was preciously constructed, and then a photocatalysis reaction of interlayer CO₃ ^2- reduction with glycerol oxidation was performed as driving force to induce the electron storage on LDH layers. With the participation of pre-stored electrons, CO₂ was captured to recover interlayer CO₃ ^2- in presence of H₂ O, accompanied with equivalent H₂ production. During photocatalysis reaction, Cu_0.6 Mg_1.4 Fe₁ exhibited a decent CO evolution amount of 1.63 mmol g^-1 and dihydroxyacetone yield of 3.81 mmol g^-1 . In carbon-negative H₂ production process, it showed an exciting CO₂ capture quantity of 1.61 mmol g^-1 and H₂ yield of 1.44 mmol g^-1 . Besides, this system possessed stable operation capability under simulated flu gas condition with negligible performance loss, exhibiting application prospect.