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Designing nanozymes with photoactivity for CO 2 reduction presents a considerable challenge. Here, a hierarchical ZFs-tpyNi nanozyme, featuring a terpyridine-based Ni complex supported on ZrO 2 nanoframes, was created using an interfacial engineering strategy for efficient CO 2 reduction under visible light. ZFs-tpyNi exhibits superior photocatalytic CO 2 -to-CO conversion, achieving a CO yield of 18.2 µmol and a selectivity of 92.4 %, with a high apparent quantum efficiency of 0.96 % in 3 h. [Display omitted] • A novel nanozyme with ZrO 2 framework and active tpyNi has been designed rationally. • Meso - and macropore in nanozyme improves the catalytic mass transfer process. • Robust framework effectively avoids the easy agglomeration between nanomaterials. • Spatially heterogeneous interface accelerates electron separation and transport. • Nanozyme achieves CO selectivity 18.2 µmol and a selectivity of 92.4 % in 3 h. Designing and fabricating nanozymes with photoactivity for CO 2 reduction poses a significant challenge. Here, a hierarchically structured ZFs-tpyNi heterojunction nanozyme, comprising a terpyridine-based Ni complex supported on ZrO 2 nanoframes, has been created through an interfacial engineering strategy for efficient CO 2 reduction under visible light. Due to its unique structural and compositional advantages, ZFs-tpyNi demonstrates superior photocatalytic CO 2 -to-CO conversion compared to its counterpart of ZFs and tpyNi, achieving a CO yield of 18.2 µmol and a selectivity of 92.4 % with a high apparent quantum efficiency of 0.96 % in 3 h. These innovative catalysts also show excellent durability for at least eight cycles without a loss in performance, maintaining a remarkable structural stability with no obvious collapse of its framework and morphology. Systematic investigations reveal that ZFs-tpyNi heterostructures exhibit a high specific surface area advantageous for the effective loading of tpyNi and exposure of active sites. The robust ZFs framework, characterized by extensive porosity, prevents nanoparticle agglomeration and accelerates mass transfer during catalysis. Additionally, the spatially heterogeneous interface enables precise modulation of band alignment and bandgap dynamics in nanozymes, enhancing light absorption and promoting the generation and separation of photogenerated charge carriers. Consequently, the nanozyme demonstrates enhanced CO 2 adsorption and activation capabilities, leading to improved selectivity of catalytic products. This work aims at highlight the role of nanozyme catalysts in sustainable energy production. [ABSTRACT FROM AUTHOR]

Photoconversion of CO 2 into value-added fuels has aroused widespread interest; however, this process is significantly limited by the inefficient thermodynamics and sluggish reaction dynamics in the diluted CO 2. To circumvent these obstacles, we design a bipyridine-based polyimide polymer for anchoring single Ni site for diluted CO 2 photoreduction. The desired Ni single atomic catalysts achieve high generation activity of ∼ 2262 μmol/h with apparent quantum efficiency (A.Q.E.) of 0.20% for CO 2 -to-CO in 0.1 atm CO 2 pressure. No measurable H 2 is produced in the catalytic process, affording nearly 100% CO selectivity over water splitting. This superior activity and selectivity outperform most previous atomical catalysts. Mechanistic analyses elucidate that the highly dispersed Ni atoms act as active sites for effective CO 2 binding and activation, and stabilize the rate-determining step of intermediates for CO generation. This work discloses the relationship between catalytic properties and single atoms for efficient solar-driven diluted CO 2 reduction. [Display omitted] • A novel Bpy-based polyimide polymer was fabricated for anchoring single Ni site. • Single-atom strategy leads to simultaneous increase of activity and selectivity. • Optimized Ni SACs for diluted CO 2 photoreduction to CO with nearly 100% selectivity. • CO 2 binding and activation with regulated intermediate are key for CO 2 reduction. [ABSTRACT FROM AUTHOR]

Photoreduction of diluted CO 2 is an effective strategy for the sustainable and environmentally friendly development of energy. In this study, lattice strain in NiSe is modulated through the control of the Ni concentration for the photoreduction of diluted CO 2. Refined XRD data and the results of the Williamson–Hall analysis indicate that the lattice strain is induced by lattice distortion caused by an absence of Ni atoms in the crystal lattice. In pure CO 2 , the cumulative CO yield and selectivity of Ni 1−x Se nanoflowers reached approximately 19.39 µmol and 90.7 % in 3 h, respectively. For lower CO 2 concentrations of 0.1 and 0.05 atm, the CO selectivity of Ni 1−x Se was approximately 72.7 % and 61.7 %, respectively. On characterization of the synthesized nanoflowers, we deduced that the lattice-strained Ni 1−x Se exhibited a favorable electronic band structure that improved the separation efficiency of the photogenerated carriers. DFT calculations results revealed that the lattice strain significantly facilitated the adsorption and activation of CO 2 , which resulted in highly efficient CO 2 photoreduction. This study provides an effective strategy for the design and synthesis of high-performance catalysts based on the modification of their crystal structures. [Display omitted] • Lattice-strained Ni 1−x Se nanoflowers were synthesized using the solvothermal method. • Lattice strain could be adjusted by modulating the Ni concentration. • Lattice-strained catalysts were utilized for the photoreduction of diluted CO 2. • Ni 1−x Se exhibited effective photocatalytic conversion of diluted CO 2 to CO. [ABSTRACT FROM AUTHOR]

While semiconductor nanocrystals with different crystal forms typically show different catalytic performances, such behavior has been scarcely documented for metal-organic frameworks (MOFs). Herein, two Ni-MOF catalysts with different crystal forms have been successfully prepared and used in photo-reduction of CO 2. With a prolonged lifetime (5 h vs 2 h) and higher yield of the product CO (34 μmol vs 18 μmol), Ni-MOF(H 2 O) demonstrates a much better performance than Ni-MOF. Theoretical studies reveal that the adsorption energy of a CO 2 molecule is more negative on Ni-MOF(H 2 O) than on Ni-MOF (−0.85 eV vs −0.62 eV). Furthermore, the transfer and separation of the photo-generated charge carriers are also more efficient in the Ni-MOF(H 2 O) system. This study not only presents a superior Ni-MOF catalyst but also promotes the fabrication of highly active catalysts for the photo-reduction of CO 2. [Display omitted] • Ni-MOF catalysts with different crystal forms have been fabricated via a facile process for the first time. • Ni-MOF(H 2 O) exhibits a much better performance than the Ni-MOF in photo-reduction of CO 2. • Ni-MOF(H 2 O) system exhibits stronger adsorption ability for CO2 molecules and lower charge transfer resistance. • Ni-MOF(H 2 O) system also exhibits lower recombination rate of photo-generated charge carriers. [ABSTRACT FROM AUTHOR]

• Novel frameworks with metalloporphyrin (ZFs-TCPP-Ni) have been constructed. • ZFs-TCPP-Ni framework serves as biomimetic photocatalyst to CO 2 photoreduction. • The biomimetic system exhibits a remarkable photocatalytic CO 2 -to-CO conversion. The development of biomimetic catalysis for efficient photoreduction of CO 2 is an effective alternative to address energy problems. However, amelioration on the construction of biomimetic catalysts for elevated photocatalytic performance is still challenging and demanded. Herein, a bioinspired artificial photosynthesis system is constructed based on ZrO 2 nanoframes (ZFs) and metalloporphyrin to mimic the morphology of trees. The robust backbone of the framework and the bio-inspiring porphyrins anchored on the surface of ZFs function as the strong trunk and well-ordered leaves of a tree, respectively. The biomimetic system achieves an evolution yield of 35.3 μmol during 3 h reaction with 93.1% CO selectivity and 1.84% CO apparent quantum efficiency (A.Q.E.), which is about 60.8 times larger than that of pure porphyrin (Ni) (0.58 μmol). Detailed analysis reveals that the catalytic system could not only achieve fast separation of the photogenerated carriers and effective CO 2 activation but also possess suitable energy levels, which could efficiently transfer electrons to the Ni catalytic sites to improve the photocatalytic activity. Furthermore, the good recycling tests could be explained by the robust supporting of frameworks as well as the strong binding of the Zr atoms and carboxyl groups of porphyrins. This work presents a simple model of biomimetic catalysts and outlines possible strategies for other biomimetic manufactures. [ABSTRACT FROM AUTHOR]

Photochemical CO 2 reduction to CO, acting as a mild and feasible method, holds huge prospects for atmospheric CO 2 level diminution. Non-noble metal aerogel has been supposed to be an appealing material in the field of catalysis, yet suffering from low conductivity and poor activity. From the perspective of electronic structure modification, oxygen-incorporated Ni aerogel is prepared by a facile reduction-oxidation method. With the optimized electronic structure in Ni@NiO-2 aerogel by oxygen incorporation, brilliant photocatalytic activity with CO yield of 39.30 μmol/mg and CO selectivity of 94.4 % could be achieved, taking advantage of the electron-rich Ni and greatly increased conductivity as well as sufficient active sites exposure. This work sheds light on the design and development of high-performance non-noble metal-based systems for catalytic CO 2 utilization. [Display omitted] • Nickel metal aerogel with porous network morphology exhibited outstanding activity. • Oxygen incorporation tuning leads to the electronic structure modification of Ni. • Optimized Ni with high conductivity promotes charge separation and CO 2 adsorption. • In situ FTIR and Mott-Schotty analysis imply the CO 2 -CO photoconversion mechanism. [ABSTRACT FROM AUTHOR]

According to the specific binding characteristic of transition metal ions with small molecules, by adjusting the ratio of Fe MOFs/Ni MOFs upcycled from industrial waste, widely tunable syngas has been produced from low-concentration CO 2 photoreduction for the first time, offering a new possibility for sustainable future industry. • Via a gradient-upcycling strategy, solid wastes can be converted into diverse MOFs. • The as-prepared Ni MOFs show a record-high performance for CO 2 -to-CO photoconversion. • By tuning Fe/Ni MOFs ratio, widely tunable syngas was produced from CO 2 photoreduction. • The diverse selectivity of Fe/Ni MOFs stems from their different affinities towards CO 2 /H 2 O. • Confirmed the universality of gradient-upcycling and modular catalysts design approach. Industrial wastes such as electroplating sludges and anthropogenic CO 2 , are misplaced resources whose utilization is severely hampered by their complex compositions or low concentration. Herein, on the basis of the specific binding characteristic of metal ions with small molecules, we demonstrate gradient-upcycling of solid wastes into different metal-organic frameworks (MOFs) for anthropogenic CO 2 -to-syngas photoconversion. In low-concentration CO 2 (10%), the as-prepared Ni MOFs exhibits record-high performance for CO 2 -to-CO photoconversion, while Fe MOFs favors for H 2 production. By taking Fe/Ni MOFs as the modular catalysts and adjusting their ratio, syngas with a widely tunable CO/H 2 ratio (1:15-14:1) was produced from CO 2 photoreduction. The diverse catalytic performance of Fe/Ni MOFs originates from the different affinities towards CO 2 /H 2 O, which relates to the 3d electron numbers of metal ions. We further confirm the universality of the gradient recovery approach to upcycle metal resources from solid wastes and the modular catalysts design approach for CO 2 -to-syngas photoconversion. [ABSTRACT FROM AUTHOR]