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The integration of oxidation and reduction half-reactions to amplify their synergy presents a considerable challenge in CO2photoconversion. Addressing this challenge requires the construction of spatially adjacent redox sites while suppressing charge recombination at these sites. This study introduces an innovative approach that utilizes spatial synergy to enable synergistic redox reactions within atomic proximity and employs spin polarization to inhibit charge recombination. We incorporate Mn into Co3O4as a catalyst, in which Mn sites tend to enrich holes as water activation sites, while adjacent Co sites preferentially capture electrons to activate CO2, forming a spatial synergy. The direct H transfer from H2O at Mn sites facilitates the formation of *COOH on adjacent Co sites with remarkably favorable thermodynamic energy. Notably, the incorporation of Mn induces spin polarization in the system, significantly suppressing the recombination of photogenerated charges at redox sites. This effect is further enhanced by applying an external magnetic field. By synergizing spatial synergy and spin polarization, Mn/Co3O4exhibits a CH4production rate of 23.4 μmol g–1h–1from CO2photoreduction, showcasing a 28.8 times enhancement over Co3O4. This study first introduces spin polarization to address charge recombination issues at spatially adjacent redox sites, offering novel insights for synergistic redox photocatalytic systems.

The factors controlling the catalytic activity in photochemical hydrogen evolution reaction (HER) are studied in detail for two macrocyclic cobalt compounds bearing two N-heterocyclic carbenes and two pyridyl donors (Co-NHC1and Co-NHC2, where Co-NHC2has a methoxy substituent on each pyridyl ligand). The present study adopts an aqueous photosystem consisting of EDTA, [Ru(bpy)3]2+(bpy = 2,2′-bipyridine), and MV2+(MV2+= methylviologen) at pH = 5. Both catalysts are shown to promote HER in a similar efficiency (TON = 12–13 in 6 h), revealing a minor contribution of the electron-donating methoxy substituents. The catalyst degradation is shown to proceed during the photocatalysis, leading to afford [Co(edta)]−(EDTA = H4edta) as a dead-end species. The lack of any heterogeneous species was evidenced by DLS (dynamic light scattering). It was also found that nitrate involved as a counteranion in the photocatalysis components substantially inhibits the photocatalytic HER, giving rise to a large diminishment in TON from 12.7 to 7.2. The Griess test was used to confirm that NO3–serves as a scavenger deactivating the reduced form of MV2+(i.e., MV+·). The detailed spectroscopic study reveals that the radical dimer (MV+·)2plays a key role in promoting the one-step two-electron process: (MV+·)2+ NO3–+ 2H+→ 2MV2++ NO2–+ H2O. Experimental and DFT results also reveal that a unique double CPET (concerted proton–electron transfer) pathway is taken to evolve H2by the Co-NHC catalysts with substantially minimized reorganization energies: Co(II)-NHC →CPETCo(III)(H)-NHC →CPETCo(II)-NHC + H2. This pathway can be viewed as related to the so-called Volmer-Heyrovsky mechanism adopted by some metals and is quite unique to the Co-NHC catalysts.

An oxocarbenium-olefin cross metathesis occurs during Brønsted acid catalyzed reactions of 1H-isochromene acetals with vinyl diazo compounds. Formally a carbonyl-alkene [2 + 2]-cyclization between isobenzopyrylium ions and the vinyl group of vinyl diazoesters, the retro-[2 + 2] cycloaddition produces a tethered alkene and a vinyl diazonium ion that, upon loss of dinitrogen, undergoes a highly selective carbocationic cascade rearrangements to diverse products whose formation is controlled by reactant substituents. Polysubstituted benzobicyclo[3.3.1]oxocines, benzobicyclo[3.2.2]oxepines, benzobicyclopropane, and naphthalenes are obtained in good to excellent yields and selectivities. Furthermore, isotopic tracer and control experiments shed light on the oxocarbenium-olefin metathesis/rearrangement process as well as on the origin of the interesting substituent-dependent selectivity.

A cytochrome cheme protein was recently engineered to catalyze the formation of carbon–silicon bonds via carbene insertion into Si–H bonds, a reaction that was not previously known to be catalyzed by a protein. High chemoselectivity toward C–Si bond formation over competing C–N bond formation was achieved, although this trait was not screened for during directed evolution. Using computational and experimental tools, we now establish that activity and chemoselectivity are modulated by conformational dynamics of a protein loop that covers the substrate access to the iron–carbene active species. Mutagenesis of residues computationally predicted to control the loop conformation altered the protein’s chemoselectivity from preferred silylation to preferred amination of a substrate containing both N–H and Si–H functionalities. We demonstrate that information on protein structure and conformational dynamics, combined with knowledge of mechanism, leads to understanding of how non-natural and selective chemical transformations can be introduced into the biological world.

We present a theoretical design of the singlet-fission (SF) interconversion between two hydrogen tautomers to attract attention to electronic devices such as switches in the SF field. We develop a tuned π-electron conjugation strategy based on single-hydrogen migration to introduce diradical character and yield low-lying E(T1) levels. Specifically, these objectives could be accomplished by moving one hydrogen from a dihydrogen-substituted pyrazine-fused ring to another unsubstituted pyrazine-fused ring in tetraazatetracenes. The predicted SF efficiency would be expected to exceed 120%. To guide future SF design development, one rule of thumb regarding the S0-state and T1-state emerges from our research: In the S0-state, single-hydrogen migration is crucial for effectively localized electrons, which are the key factor in the formation of diradicals. Conversely, single-hydrogen migration induces a large area of π-electron conjugation in the T1-state, which is completely applied to the electron–hole interaction in the S0→ T1transition, thereby providing low-lying E(T1) levels. Furthermore, a series of hydrogen tautomers of tetraazaacenes have been proposed as diradicaloid SF switches to verify the reliability of the above rule of thumb. This study will not only help researchers in the photovoltaic field to obtain the desired E(T1) in the future but also broaden the application of hydrogen migration in photovoltaic switch research and supplement the SF database.

Solar energy-assisted water oxidative hydrogen peroxide (H2O2) production on an anode combined with H2production on a cathode increases the value of solar water splitting, but the challenge of the dominant oxidative product, O2, needs to be overcome. Here, we report a SnO2–xoverlayer coated BiVO4photoanode, which demonstrates the great ability to near-completely suppress O2evolution for photoelectrochemical (PEC) H2O oxidative H2O2evolution. Based on the surface hole accumulation measured by surface photovoltage, downward quasi-hole Fermi energy at the photoanode/electrolyte interface and thermodynamic Gibbs free energy between 2-electron and 4-electron competitive reactions, we are able to consider the photoinduced holes of BiVO4that migrate to the SnO2–xoverlayer kinetically favor H2O2evolution with great selectivity by reduced band bending. The formation of H2O2may be mediated by the formation of hydroxyl radicals (OH·), from 1-electron water oxidation reactions, as evidenced by spin-trapping electron paramagnetic resonance (EPR) studies conducted herein. In addition to the H2O oxidative H2O2evolution from PEC water splitting, the SnO2–x/BiVO4photoanode can also inhibit H2O2decomposition into O2under either electrocatalysis or photocatalysis conditions for continuous H2O2accumulation. Overall, the SnO2–x/BiVO4photoanode achieves a Faraday efficiency (FE) of over 86% for H2O2generation in a wide potential region (0.6–2.1 V vs reversible hydrogen electrode (RHE)) and an H2O2evolution rate averaging 0.825 μmol/min/cm2at 1.23 V vs RHE under AM 1.5 illumination, corresponding to a solar to H2O2efficiency of ∼5.6%; this performance surpasses almost all previous solar energy-assisted H2O2evolution performances. Because of the simultaneous production of H2O2and H2by solar water splitting in the PEC cells, our results highlight a potentially greener and more cost-effective approach for “solar-to-fuel” conversion.

It has long remained challenging to predict the properties of complex chemical systems, such as polymer-based materials and their composites. We have constructed the largest database of lithium-conducting solid polymer electrolytes (104entries) and employed a transfer-learned graph neural network to accurately predict their conductivity (mean absolute error of less than 1 on a logarithmic scale). The bias-free prediction by the network helped us to find superionic conductors composed of charge-transfer complexes of aromatic polymers (ionic conductivity of around 10–3S/cm at room temperature). The glassy design was contrary to the traditional concept of rubbery polymer electrolytes, but it was found to be appropriate to achieve fast, decoupled motion of ionic species from polymer chains and to enhance thermal and mechanical stability. The unbiased suggestions generated by machine learning models can help researches to discover unexpected chemical phenomena, which could also induce a paradigm shift of energy-related functional materials.

The all-inorganic α-CsPbI3perovskite with the most suitable band gap faces serious challenges of low phase stability and high moisture sensitivity. We discover that a simple phenyltrimethylammonium bromide (PTABr) post-treatment could achieve a bifunctional stabilization including both gradient Br doping (or alloying) and surface passivation. The PTABr treatment on CsPbI3only induces less than 5 nm blue shift in UV–vis absorbance but significantly stabilize the perovskite phase with much better stability. Finally, the highly stable PTABr treated CsPbI3based perovskite solar cells exhibit a reproducible photovoltaic performance with a champion efficiency up to 17.06% and stable output of 16.3%. Therefore, this one-step bifunctional stabilization of perovskite through gradient halide doping and surface organic cation passivation presents a novel and promising strategy to design stable and high performance all-inorganic lead halide.