Engineering electronic interaction between cobalt single atom and polymeric carbon nitride for hydrogen peroxide efficient photosynthesis.

Photocatalytic CO2 reduction into value-added fuels using water as the electron donor represents a sustainable route for artificial photosynthesis, yet it is often hindered by rapid charge recombination and insufficient thermodynamic driving force. Herein, we report a ternary heterojunction photocatalyst composed of zero-dimensional Ti3C2 quantum dots (QDs) and metallic Cu comodified on two-dimensional g-C3N4 (denoted as CCNT). The Cu nanoparticles broaden the visible-light absorption and negatively shift the conduction band of g-C3N4, providing a strong driving force for CO2 reduction. Meanwhile, the highly conductive Ti3C2 QDs act as efficient electron reservoirs, rapidly extracting photogenerated electrons from Cu/g-C3N4 and redistribute photogenerated electrons. This prevents charge accumulation at Cu sites, stabilizes the reduction centers, and maintains electron-hole balance. The optimized CCNT-5 composite achieves CO and CH4 production rates of 24.59 and 20.24 μmol g-1 h-1 under visible light, resulting an electron selectivity toward CO2 reduction as high as 94.90%. Moreover, the catalyst enables simultaneous water oxidation with a nearly 1:1 electron-to-hole consumption ratio and excellent long-term stability. This work demonstrates a rational 0D/metal/two-dimensional (2D) architecture for efficient and stable solar-driven CO2 reduction.

Photocatalytic H2O2 synthesis via the two-electron O2 reduction reaction (2e- ORR) is attractive, yet the interplay between active-site-mediated excited-state electron behavior and in situ O2 activation at the atomic scale remains unclear. Herein, we establish a mechanism-guided integrated strategy combining theoretical screening, experimental construction, and in situ characterization to identify Ta single-atom sites as the optimal 5d metal centers on carbon nitride for H2O2 photosynthesis. The resulting catalyst combines favorable excited-state charge localization with thermodynamic advantages for the 2e- ORR, achieving an apparent quantum yield of 14.53% at 420 nm and a solar-to-chemical conversion efficiency of 1.12% in pure water. Multidimensional in situ spectroscopy measurements and theoretical calculations demonstrate that Ta single-atom sites act as dynamically adaptive catalytic centers through flexible in situ valence-state evolution (+4.16 → +4.37 → +3.14), facilitating initial O2 adsorption and then accumulating and transferring excited-state electrons to drive end-on O2 activation through Ta 5d-O 2p orbital coupling, thereby accelerating *OOH-mediated selective H2O2 formation. This work establishes a framework for understanding dynamic single-atom photocatalysis and guiding the design of adaptive active sites for artificial H2O2 photosynthesis.

Biotic-abiotic interfaced configurations hold great promise for application in renewable energy and artificial photosynthesis systems. Recent advances in synthetic biology, computational, and visualization techniques, along with enhanced high-resolution characterization, have enabled a deeper fundamental understanding of the interface, which, in turn, has improved electron transfer processes and the design architecture. These developed configurations open new routes to mimic the photosynthetic apparatus or add new applications based on biotic and abiotic catalytic reactions. Aiming to surpass natural systems, researchers have examined methods to reconfigure these block sets into new designs. This review focuses on the advances in artificial photosynthesis and coupled biotic-abiotic biohybrid systems. The work presents the development of artificial photosynthesis configurations aimed at generating light-induced energy or fuels. The use of natural photosynthetic proteins, inorganic photocatalysts, and advanced biohybrid materials is presented and discussed, aiming to enable future biotic-abiotic design and the ambitious goal of developing real-world applications.

Artificial photosynthesis has emerged as a promising strategy for sustainable solar-to-chemical energy conversion by mimicking natural photosynthetic processes to produce fuels from water and carbon dioxide. In recent years, significant chemical advances have been achieved in light-harvesting materials, molecular and heterogeneous catalysts, and integrated photoelectrochemical systems. Progress in self photosensitizing molecular catalysts, metal-organic and covalent organic frameworks, and earth-abundant water oxidation and CO2 reduction catalysts has enhanced charge separation, catalytic efficiency, and product selectivity. Meanwhile, artificial leaf architectures and hybrid systems have demonstrated improved solar-to-chemical conversion efficiencies under increasingly practical conditions. Notably, several laboratory scale photoelectrochemical (PEC) systems have recently reported solar-to-hydrogen conversion efficiencies approaching 10% (unassisted, AM 1.5G illumination), reaching the threshold for commercial viability. Despite these advances, challenges related to long-term catalyst stability, efficiency losses, and large-scale implementation remain. This review summarizes key chemical developments from the past 3–5 years (2020–2025), highlighting emerging design strategies and integrated approaches that are shaping the future of scalable and sustainable artificial photosynthesis.

The development of photosensitizing materials synergizing broad-spectrum harvesting with long-lived excited states is pivotal for advancing artificial photosynthesis. Herein, we propose a precoordination-induced coassembly strategy to integrate complementary chromophores into unsaturated Cu-MOFs (Cu-0 - Cu-123), enabling synergistic tuning of their photon absorption channels and excited states. The cosensitized Cu-123 exhibits panchromatic absorption across 200-700 nm and a prolonged excited-state lifetime of 10.2 μs via a "ping-pong" cascade energy transfer, which is over 200-fold longer than that in the pristine framework of Cu-0 (<0.05 μs). Remarkably, it achieves an outstanding yield (76.4%) in artemisinin photosynthesis and demonstrates exceptional versatility across a diverse range of organic transformations (>10 distinct reactions). Gram-scale synthesis under sunlight achieved via the construction of a continuous-flow photoreactor indicates its potential for scalable solar energy conversion. This work not only presents highly efficient photocatalysts but also establishes a general method for constructing porous photosynthesis systems with tailored photophysical properties for solar-to-chemical conversion.

Biosynthesis of C-phycocyanin trimers.

Efficient excited-state energy transfer (ET) is fundamental to artificial photosynthesis and solar energy conversion, yet conventional heterogeneous composites commonly suffer from nonradiative interfacial losses and limited structural precision. Herein, we report a family of multivariate porphyrin-based three-dimensional covalent organic frameworks (3D COFs) with bcu topology, in which electronically complementary benzimidazole donor and benzoselenadiazole acceptor chromophores are periodically integrated within a single crystalline lattice. The resultant TS-PCOF displays broadened visible-light absorption and pronounced donor-acceptor spectral overlap. Combined steady-state and time-resolved spectroscopic analyses reveal efficient intraframework ET on a sub-nanosecond timescale, delivering an ET efficiency of up to 23.8%. This work highlights multivariate 3D COFs as structurally precise platforms for programmable light harvesting and directional energy migration, providing a promising strategy for advanced photonic and solar-energy-conversion systems.

Ultrathin metal-organic layers (MOLs) have emerged as a type of promising two-dimensional (2D) platforms for artificial photosynthesis, yet their activity is frequently limited by rapid recombination of photogenerated carriers in presence of structural symmetry. Hence, switching on the reactivity through breaking geometric symmetry to create unsymmetric active sites remains a significant challenge. Herein, we demonstrate a switching strategy via one-atom substitution to construct two isostructural ultrathin MOLs with distinct coordination symmetry at the iron active site. Single-crystal x-ray diffraction and spectroscopic analyses reveal that symmetry breaking at the iron site in the MOL effectively enhances CO2 adsorption and facilitates photogenerated carrier separation. Under visible-light irradiation, the MOL with unsymmetrical sites achieves an exceptional CO production amount (ca. 21.20mmol·g-1), which is as high as 15.8 times more than that of its symmetrical counterpart. Time-resolved transient absorption spectroscopy corroborated by DFT calculations indicates that symmetry breaking not only accelerates the separation and transport of photogenerated charge carriers, but also lowers the Gibbs free energy of CO2 adsorption. This work elucidates how the atomically precise modification of local coordination symmetry switches the photocatalytic performance in an 'off/on' manner and provides a viable design strategy toward emerging 2D materials for artificial photosynthesis.

Mimicking natural photosynthesis to split water into oxygen and hydrogen represents a promising pathway for transitioning from fossil fuels to a sustainable energy future. It is extremely challenging to duplicate the efficient and elegant oxygen evolution complex of photosynthesis II of oxidizing water to O2 being regarded as the bottleneck of water splitting. Cutting-edge artificial molecular water oxidation catalysts (WOCs) with low overpotentials are highly desirable for efficient water oxidation. Here we report the design of a molecular water oxidation catalyst (WOC) RuN5 (Ru(N5)(pic)2; N5= 4-tert-butyl-2,6-di(1',8'-naphthyrid-2'-yl)pyridine, pic= 4-picoline). Following electrochemical activation and bromide mediation, RuN5 achieves a high turnover frequency of 2604s-1 with a low overpotential of 363mV at pH 7. The catalyst is highly stable, maintaining a steady current density of 1.8mAcm-2 over 200h. Mechanistic studies reveal that activation and bromide mediation facilitate O-O bond formation via a ligand-oxidized [RuIV═O]2+ intermediate through a low energy pathway, distinct from the classical [RuV(O)]3+ route. This work opens a new avenue for developing efficient molecular WOCs and advancing artificial photosynthesis.

Microbial artificial photosynthesis offers a promising strategy for light-driven biomanufacturing, yet its efficiency remains limited by the non-selective conversion of photogenerated electrons into metabolically usable reducing power, causing energy dissipation and weak coupling between light capture and metabolic reactions. Here, we report a rational strategy using riboflavin (RF), a membrane-permeable and biocompatible flavin photosensitizer, to selectively channel photonic energy into intracellular NADPH regeneration. Quantum chemical calculations and spectroscopic analyses reveal that light-excited RF exhibits a specific binding affinity and favorable electron transfer trend toward NADP+. In vivo, RF activation markedly elevated intracellular NADPH levels and enhanced the synthesis of NADPH-dependent metabolites through NADPH reductase-associated pathways. Transcriptomic and inhibition analyses linked RF-mediated NADPH regeneration to NADP+/NADPH redox enzymes rather than glucose-6-phosphate dehydrogenase-mediated flux, while NADH-related redox genes remained largely unaffected, demonstrating the selectivity of this reductive route. Cross-species and multi-product validations consistently reproduced these results, underscoring the generality of this mechanism across distinct NADPH-dependent microbial chassis. This work establishes a mechanistically defined and broadly applicable framework for directing photogenerated electrons into specific cellular reducing equivalents, paving the way for efficient artificial photosynthetic and bioelectrochemical platforms.

Understanding how microsolvation influences the reactivity and stability of molecular water-oxidation catalysts remains a central challenge in artificial photosynthesis. Here, we combine molecular dynamics (MD) simulations with spectroscopic and electrochemical experiments to elucidate how acetonitrile/water mixtures organize around the mixed-valence polyoxometalate [(Mn4O4) (V4O13) (OAc)3]n- across catalytically relevant redox states. Our results reveal a pronounced oxidation-state dependence: the reduced species is surrounded by a dense, highly structured hydration shell even at low water contents, preferentially engaging terminal vanadate oxygen sites and partially displacing acetonitrile from the first solvation shell. By contrast, the oxidized and species show substantially weaker water structuring and largely oxidation state-insensitive acetonitrile organization. These microscopic solvation motifs are directly reflected experimentally: spectroscopic titrations reveal the emergence of hydrogen-bond formation at V═O groups and Jahn-Teller-driven asymmetric solvent accumulation accompanied by ligand exchange, while electrochemical measurements indicate reduced diffusion coefficients and diminished redox features at higher water contents, consistent with ion pair-mediated aggregation observed in MD simulations. Together, these results establish oxidation state as a key control parameter for solvent organization around polyoxometallate water-oxidation catalysts and provide a molecular rationale for the enhanced activity yet limited stability window of species in acetonitrile/watermixtures.

Quantum tunneling offers a fascinating paradigm for orchestrating spatial charge transport in artificial photosynthesis. However, precisely manipulating electron tunneling across well-defined heterointerfaces remains a formidable challenge, with conventional designs largely confined to classical Semiconductor–Insulator–Metal (S–I–M) architectures. Herein, we report a conceptual endeavor by fundamentally departing from the traditional S–I–M model, constructing a unique and novel semiconductor–insulator–ligand/metal tunneling platform. Specifically, an ultrathin insulating poly(sodium 4-styrenesulfonate) (PSS) layer is engineered onto a transition metal chalcogenide (TMC, e.g., CdS) substrate. Subsequently, poly(diallyldimethylammonium chloride) (PDDA)-capped metal nanocrystals (M@PDDA, M = Au, Pd) are precisely anchored via electrostatic self-assembly, yielding well-defined TMC@PSS/M@PDDA heterostructures. Distinct from conventional systems, the PDDA ligands synergistically couple with the metal core to form an integrated, highly potent electron capture center driven by the Schottky-junction effect. This unique synergistic driving force triggers non-classical, directional electron tunneling from the photoexcited TMC substrate directly through the insulating PSS barrier. Benefiting from this advantageous quantum tunneling, TMC@PSS/M@PDDA heterostructures demonstrate significantly enhanced and multifarious visible-light-driven photoredox activities including selective organic transformations and H2O2 production. This work establishes an elegant conceptual paradigm for decoding and customizing quantum tunneling pathways, offering profound fundamental insights into advanced solar energy conversion.

ABSTRACT Artificial photosynthesis that mimics overall photosynthesis towards converting CO 2 and H 2 O to C 2+ chemicals still remains a great challenge due to the lack of efficient photocatalysts containing both water oxidation reaction (WOR) and CO 2 reduction reaction (CO 2 RR) active sites with good visible‐light absorption capability and matched band structure. Herein, we developed a three‐dimensional covalent organic framework (3D COF), BPDA‐AmCOF‐Ce, containing paired Ce(III) single atomic sites and pyrene moieties. The two‐fold interpenetrated bcu topology of BPDA‐AmCOF‐Ce with two neighboring 2,2'‐bipyridine moieties of BPDA results in a short distance of 5.63 Å for paired Ce atoms, capable of inducing C‐C coupling in CO 2 RR. This, together with exposed pyrene moieties‐effective in driving 2e − WOR, good visible light absorption capacity, and matched band structure, enables BPDA‐AmCOF‐Ce to exhibit excellent overall photosynthesis performance, converting CO 2 and H 2 O to CH 3 COOH and H 2 O 2 at high production rates of 166.67 and 601.42 µmol g catalyst −1 h −1 , respectively, with selectivity upto 94.4% under visible light ( λ &gt; 420 nm) illumination. This work not only provides insights into the design and fabrication of efficient artificial photocatalysts to mimic overall photosynthesis but also highlights the significance of combining COFs with single‐atom catalysts towards engineering reaction pathways in photocatalysis.

Artificial photosynthesis that mimics overall photosynthesis towards converting CO2 and H2O to C2+ chemicals still remains a great challenge due to the lack of efficient photocatalysts containing both water oxidation reaction (WOR) and CO2 reduction reaction (CO2RR) active sites with good visible-light absorption capability and matched band structure. Herein, we developed a three-dimensional covalent organic framework (3D COF), BPDA-AmCOF-Ce, containing paired Ce(III) single atomic sites and pyrene moieties. The two-fold interpenetrated bcu topology of BPDA-AmCOF-Ce with two neighboring 2,2'-bipyridine moieties of BPDA results in a short distance of 5.63 Å for paired Ce atoms, capable of inducing C-C coupling in CO2RR. This, together with exposed pyrene moieties-effective in driving 2e- WOR, good visible light absorption capacity, and matched band structure, enables BPDA-AmCOF-Ce to exhibit excellent overall photosynthesis performance, converting CO2 and H2O to CH3COOH and H2O2 at high production rates of 166.67 and 601.42 µmol gcatalyst -1 h-1, respectively, with selectivity upto 94.4% under visible light (λ > 420 nm) illumination. This work not only provides insights into the design and fabrication of efficient artificial photocatalysts to mimic overall photosynthesis but also highlights the significance of combining COFs with single-atom catalysts towards engineering reaction pathways in photocatalysis.

Solar-driven CO2 reduction offers a sustainable route to carbon neutrality by converting greenhouse gases into value-added fuels. Here, we report a secondary coordination sphere design strategy that directs CO2 photoreduction selectivity toward methane (CH4). A redox-active Ni complex (C1), incorporating two (6-amino-2-(phenylazo)pyridine) ligands with a pendant amine, exhibits markedly enhanced CH4 selectivity compared to control complexes lacking the pendant –NH2 group. Systematic evaluation of sacrificial donors, proton sources, and photosensitizers identified a dimeric Cu(i)-based photosensitizer (Cu-PS-1) as a cost-effective alternative to Ir-based systems, achieving TONCO2→CO = 4789, TONCO2→CH4 = 1130, and TONCO→CH4 = 3102, rivalling Ir-PS-1. Operando UV-vis, FTIR, and EPR spectroscopy, together with DFT calculations, revealed a stepwise 8e−/8H+ reduction pathway in which the pendant –NH2 group stabilizes key COOH and CHx intermediates through hydrogen bonding, lowering activation barriers and steering selectivity toward CH4. These results establish OCS engineering as a powerful design principle for earth-abundant molecular catalysts and highlight new opportunities for selective CO2-to-CH4 conversion in artificial photosynthesis and carbon valorization.

Artificial photosynthesis enables the solar-driven reduction of CO2 in water to form formic acid, a C1 hydrogen carrier and renewable fuel precursor. However, selective formic acid formation in aqueous media remains fundamentally limited by inefficient interfacial proton-electron coupling. Here, we show that ionic liquids (ILs) actively mediate interfacial charge transfer through ion-pair pathways that extract and stabilize photogenerated electrons and protons, thereby enabling selective CO2 photoreduction. In this context, our iron oxide microrods exhibit high activity for formic acid production in IL-aqueous solutions under LED irradiation. Among the different ILs, 1,2-dimethyl-1-n-butyl-imidazolium 2-methylimidazolate (BMMIm.MeIm) affords the highest efficiency, achieving a yield of about 55.4 μmol (554 μmol.g-1) of formic acid with >99% selectivity and an apparent quantum yield of 4.4%. Spectroscopic analyses (EPR, NMR, and ex situ FTIR) reveal the formation of [CO2]•- and imidazolium-cation radical species, confirming the direct participation of IL in charge extraction and CO2 activation. Mössbauer spectroscopy confirmed hematite as the predominant phase and revealed an IL-induced formation of 6-9% reduced iron (Fe(0)/Fe(I)), indicating partial Fe2O3 reduction within the microrods. The IL creates an organized interfacial microenvironment that tunes band energetics, promotes charge separation, and stabilizes CO2-derived intermediates, while light-induced radical signatures indicate transient interfacial charge-transfer processes that favor selective formate production. This catalytic system also demonstrates efficiency under natural sunlight, producing 27.7 μmol (277 μmol.g-1), highlighting its adaptability and robustness. DFT calculations further reveal that IL cation-anion orientation at Fe2O3 surfaces modulates band energetics and promotes interfacial charge transfer.

Photocatalytic CO2 reduction offers a promising solar-to-chemical route, but most systems struggle to meet economic and scalability benchmarks. Current approaches fall short of the U.S. Department of Energy's Carbon Negative Shot target of < $100/t CO2 removed. Here, we develop an all-biomolecular nanophotosystem (Hb-EA) without the involvement of synthetic metal catalysts, pairing a nonenzymatic protein with a plant-derived photosensitizer. Hemoglobin (Hb), a ubiquitous oxygen-carrier protein with reversible CO2-binding and redox-active heme sites that serve as biologically embedded metal centers, is supramolecularly encapsulated by crystalline ellagic acid (EA), forming an Hb-EA nanohybrid where π-π stacking and hydrogen bonding create an organic-semiconductor-like shell with a 2.44 eV bandgap and broad visible absorption. Upon illumination, the EA shell efficiently harvests light and funnels electrons into Hb heme centers, selectively capturing and reducing CO2 to formic acid. Hb-EA achieves a benchmark-leading CO2-to-formate production rate of 397.61 μmol h-1 USD-1 with ∼93% selectivity, significantly surpassing prior systems in cost-normalized performance. This biobased photocatalyst uses no noble metals or external cocatalysts and is assembled from inexpensive biobuilding blocks. Scalability is demonstrated by a 100 × 60 cm Hb-EA membrane photoreactor under outdoor sunlight, where it maintained high activity and stability, establishing a paradigm for artificial photosynthesis linking structural biochemistry with sustainable photonic materials for green, economically viable CO2 reduction.

Covalent organic frameworks (COFs) have emerged as a promising platform for photocatalytic H2O2 production, a key reaction in artificial photosynthesis. However, the practical application of conventional benzene-rich COF skeletons is often limited by their weak oxygen adsorption capacity and inefficient charge carrier transport. To address these challenges, we report a universal post-synthetic strategy that incorporates local, electron-deficient polar single-molecule junctions into the COF framework via a straightforward one-step modification. These engineered junctions play a dual role: the localized electron-deficient sites strongly anchor and activate oxygen molecules, while the in-built polarity establishes directional channels for the migration of photogenerated charge carriers, ensuring their precise delivery to active sites. This synergistic mechanism leads to a marked enhancement in superoxide radical generation and the subsequent synthesis of H2O2. Under acidic conditions (pH = 3), the H2O2 generation rate of the monomolecularly-linked COF reached 4354µmol g-1 h-1, significantly higher than the 1655µmol g-1 h-1 of the pristine COF. The broad applicability of this design principle was firmly established through the successful implementation of a series of tailor-made analogous molecules across several distinct COF platforms.

Hydrogen peroxide (H2O2) is an essential green oxidant with broad industrial relevance. Photocatalytic oxygen reduction reaction (ORR) offers a sustainable method for producing oxygen, yet its efficiency is limited by poor charge separation and severe carrier recombination. Single-component photocatalysts suffer from sluggish carrier dynamics, while multi-energy-state systems frequently experience recombination at intermediate states. S-scheme heterojunction engineering offers an effective strategy to address these challenges by regulating interfacial charge transfer while preserving strong redox potentials. Here, we report the construction of an S-scheme photocatalyst by integrating a triazine-based covalent organic framework (COF) with sulfur-vacancy-rich Mn0.2Cd0.8S (Sv-MCS). This dual-functional design preserves both the intrinsic n→π* electronic transitions of the COF and defect-state absorption of Sv-MCS, delivering an exceptional H2O2 production rate of 5389.6 µmol·h-1·g-1 in pure water. Concurrently, the photostability of the catalyst is simultaneously enhanced. X-ray absorption fine-structural analysis confirms interfacial Cd-O coordination between Cd atoms and COF carbonyl groups. In situ spectroscopies combined with density functional theory elucidate a preferential two-electron ORR pathway, while femtosecond transient absorption spectroscopy confirms suppressed carrier recombination enabled by synergistic S-scheme charge transfer and interfacial chemical bonding. This work establishes design principles for multi-energy-state S-scheme photocatalysts and advances solar-driven H2O2 production toward artificial photosynthesis.