Regulating the spintronic structure of electrocatalysts can improve the oxygen evolution reaction performance efficiently. Nonetheless, the effects of tuning the spintronic structure for the oxygen evolution reaction mechanisms have rarely been discussed. Here, we show a ruthenium-cobalt-tin oxide with optimized spintronic structure due to the quantum spin interaction of Ru and Co. The specific spintronic structure of ruthenium-cobalt-tin oxide promotes the charge transfer kinetics and intermediates evolution behavior under applied potential, generating long-lived active species with higher spin density sites for the oxygen evolution reaction after the reconstruction process. Moreover, the ruthenium-cobalt-tin oxide possesses decoupled proton-electron transfer procedure during the oxygen evolution reaction process, demonstrating that the electron transfer procedure of O-O bond formation between *O intermediate and lattice oxygen in Co-O-Ru is the rate-determining step of the oxygen evolution reaction process. This work provides rational perspectives on the correlation between spintronic structure and oxygen evolution reaction mechanism.

A water oxidation catalyst Ru-bcs (bcs = 2,2′-bipyridine-6′-carboxylate-6-sulfonate) with a hybrid ligand was reported. Ru-bcs utilizes the electron-donating properties of carboxylate ligands and the on-demand coordination feature of sulfonate ligands to enable a low onset potential of 1.21 V vs. NHE and a high TOF over 1000 s⁻¹ at pH 7. The adaptive chemistry uncovered in this work provides new perspectives for developing molecular catalysts with high efficiency under low driving forces.

Covalent organic frameworks (COFs) have been acknowledged as a potential platform for heterogeneous photoredox cross-coupling due to their excellent chemical stability, admirable controllability, and extremely prominent surface area. However, synthesizing COFs with bidentate ligand units and utilizing active sites remain a grand challenge. Herein, we report a promising new family of 2,6-pyridinedicarboxaldehyde-bis-(p-aminophenylimine)-based two-dimensional (2D) COFs (PP-COF) using an amine monomer and classic tri-aldehydes. On this basis, dispersed Ni single-atom sites were immobilized on three-types imine-based bi-coordinated 2D COFs (Ni SAS-PP-COF) as heterogeneous dual photoredox catalysts for photo/Ni dual-catalyzed C–N cross-coupling between aryl bromides and alkyl/sulfo amines. Under solar energy irradiation, PP-COF could absorb light to generate electrons and holes, then the photogenerated electrons are transferred to Ni sites to reduce divalent nickel to monovalent nickel. Monovalent nickel is necessary to drive the nickel catalytic cycle. Due to the increased charge separation and abundant active sites, the state-of-the-art Ni SAS-PP-COFs catalyst achieves excellent catalytic performance in comparison of pristine PP-COF. The heterogeneous Ni SAS-PP-COF catalytic system not only confirms the prospect of COFs as potential photoredox/transition-metal dual catalysts, but also provides in-depth insights into the synthesis of functional COFs toward practical metallaphotocatalytic application.

Photoelectrochemical (PEC) cells provide a promising solution for the synthesis of hydrogen peroxide (H2O2). Herein, an integrated photocathode of p-type BiVO4 (p-BVO) array with tetragonal zircon structure coupled with different metal oxide (MOx, M = Sn, Ti, Ni, and Zn) heterostructure and NiNC cocatalyst (p-BVO/MOx/NiNC) was synthesized for the PEC oxygen reduction reaction (ORR) in production of H2O2. The p-BVO/SnO2/NiNC array achieves the production rate 65.46 μmol L–1 h–1 of H2O2 with a Faraday efficiency (FE) of 76.12%. Combined with the H2O2 generation of water oxidation from the n-type Mo-doped BiVO4 (n-Mo:BVO) photoanode, the unbiased photoelectrochemical cell composed of a p-BVO/SnO2/NiNC photocathode and n-Mo:BVO photoanode achieves a total FE of 97.67% for H2O2 generation. The large area BiVO4-based tandem cell of 3 × 3 cm2 can reach a total H2O2 production yield of 338.84 μmol L–1. This work paves the way for the rational design and fabrication of artificial photosynthetic cells for the production of liquid solar fuel. 

The Mn4CaO5(6) cluster in photosystem II catalyzes water splitting through the Si state cycle (i = 0–4). Molecular O2 is formed and the natural catalyst is reset during the final S3 → (S4) → S0 transition. Only recently experimental breakthroughs have emerged for this transition but without explicit information on the S0-state reconstitution, thus the progression after O2 release remains elusive. In this report, our molecular dynamics simulations combined with density functional calculations suggest a likely missing link for closing the cycle, i.e., restoring the first catalytic state. Specifically, the formation of closed-cubane intermediates with all hexa-coordinate Mn is observed, which would undergo proton release, water dissociation, and ligand transfer to produce the open-cubane structure of the S0 state. Thereby, we theoretically identify the previously unknown structural isomerism in the S0 state that acts as the origin of the proposed structural flexibility prevailing in the cycle, which may be functionally important for nature’s water oxidation catalysis.

The cobalt-coordinated polyterthiophene/hematite hybrid photoanode, denoted as Co@PTTh-N/α-Fe2O3, was fabricated to facilitate the photo-driven water oxidation reaction. The optimally aligned energy levels of the PTTh-N/α-Fe2O3 heterojunction promoted charge transfer and decreased charge recombination. The phenanthroline functional groups within PTTh-N coordinated with Co2+ ions that serve as effective catalytic centers for water oxidation, resulting in a significant enhancement of photocurrent.

Metal phthalocyanines (MPcs) have gained considerable research attention as hole-transport materials (HTMs) in perovskite solar cells (PSCs) because of their superb stability. However, the photovoltaic performance of MPc-based HTMs in PSCs is still lagging behind their small molecule and polymeric counterparts, largely due to their relatively low hole mobility. Here, we report for the first time the application of a copper naphthalocyanine derivative (namely tBu-CuNc) as a hole-transport material (HTM) in perovskite solar cells (PSCs), and systematically study its optoelectronic and photovoltaic property compared with its CuPc analog (tBu-CuPc). Combined experiments disclose that the extension of π-conjugation from Pc to Nc core leads to not only an enhanced hole-carrier mobility associated with a stronger intermolecular interaction, but also an elevated glass transition temperature (T<inf>g</inf>) of 252 °C. The resultant PSCs employing tBu-CuNc deliver an excellent power conversion efficiency of 24.03%, which is the record efficiency reported for metal complex-based HTMs in PSCs. More importantly, the encapsulated tBu-CuNc-based devices also show dramatically improved thermal stability than the devices using the well-known Spiro-OMeTAD, with a T<inf>80</inf> lifetime for more than 1,000 h under damp-heat stress. This study unfolds a new avenue for developing efficient and stable HTMs in PSCs. (Figure presented.)

Despite extensive research on water oxidation catalysts over the past few decades, the relationship between high-valent metal-oxo intermediates and the O-O bond formation pathway has not been well clarified. Our previous study showed that the high spin density on O in Ru^V=O is pivotal for the interaction of two metal-oxyl radical (I2M) pathways. In this study, we found that introducing an axially coordinating ligand, which is favorable for bimolecular coupling, into the Ru-pda catalyst can rearrange its geometry. The shifts in geometric orientation altered its O-O bond formation pathway from water nucleophilic attack (WNA) to I2M, resulting in a 70-fold increase in water oxidation activity. This implies that the I2M pathway is concurrently influenced by the spin density on oxo and the geometry organization of the catalysts. The observed mechanistic switch and theoretical studies provide insights into controlling reaction pathways for homogeneous water oxidation catalysis.

13,14-diphenyldibenzo[b,j][4,7]phenanthroline (DBP3) in various solvents was studied by time-resolved fluorescence and fs transient absorption (fs-TA) spectroscopy. An intramolecular benzene excimer is demonstrated to form within DBP3; it exhibits strong redshifted emission with maximum at 540-640 nm. "Intrinsic" fluorescence from DBP3 is dramatically quenched down to tau = 50-400 fs in all the solvents studied. Fs-TA and time-resolved fluorescence spectra have proved that relaxed intramolecular benzene excimer is formed from S1 state via hot excimer state with three lifetime components: 50 fs, similar to 3.5 ps, and similar to 25 ps, which are of the inertial (electronic) and diffusive parts of the relaxation due to solute-solvent interaction. Formation of triplet states via intersystem crossing was observed directly from the upper excited electronic states of DBP3.

The photogenerated charge carrier separation and transportation of inside photocathodes can greatly influence the performance of photoelectrochemical (PEC) H2 production devices. Coupling TiO2 with p-type semiconductors to construct heterojunction structures is one of the most widely used strategies to facilitate charge separation and transportation. However, the band position of TiO2 could not perfectly match with all p-type semiconductors. Here, taking antimony selenide (Sb2Se3) as an example, a rational strategy was developed by introducing a viologen electron transfer mediator (ETM) containing polymeric film (poly-1,1′-dially-[4,4′-bipyridine]-1,1′-diium, denoted as PV2+) at the interface between Sb2Se3 and TiO2 to regulate the energy band alignment, which could inhibit the recombination of photogenerated charge carriers of interfaces. With Pt as a catalyst, the constructed Sb2Se3/PV2+/TiO2/Pt photocathode showed a superior PEC hydrogen generation activity with a photocurrent density of −18.6 mA cm−2 vs. a reversible hydrogen electrode (RHE) and a half-cell solar-to-hydrogen efficiency (HC-STH) of 1.54% at 0.17 V vs. RHE, which was much better than that of the related Sb2Se3/TiO2/Pt photocathode without PV2+ (−9.8 mA cm−2, 0.51% at 0.10 V vs. RHE).