Supramolecular Tuning Enables Selective Oxygen Reduction Catalyzed by Cobalt Porphyrins for Direct Electrosynthesis of Hydrogen Peroxide

We report a supramolecular strategy for promoting the selective reduction of O₂ for direct electrosynthesis of H₂O₂. We utilized cobalt tetraphenylporphyrin (Co‐TPP), an oxygen reduction reaction (ORR) catalyst with highly variable product selectivity, as a building block to assemble the permanently porous supramolecular cage Co‐PB‐1(6) bearing six Co‐TPP subunits connected through twenty‐four imine bonds. Reduction of these imine linkers to amines yields the more flexible cage Co‐rPB‐1(6). Both Co‐PB‐1(6) and Co‐rPB‐1(6) cages produce 90–100 % H₂O₂ from electrochemical ORR catalysis in neutral pH water, whereas the Co‐TPP monomer gives a 50 % mixture of H₂O₂ and H₂O. Bimolecular pathways have been implicated in facilitating H₂O formation, therefore, we attribute this high H₂O₂ selectivity to site isolation of the discrete molecular units in each supramolecule. The ability to control reaction selectivity in supramolecular structures beyond traditional host–guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications.     

Large‐Area,Free‐Standing,Two‐Dimensional Supramolecular Polymer Single‐Layer Sheets for Highly Efficient Electrocatalytic Hydrogen Evolution

The rational construction of covalent or noncovalent organic two‐dimensional nanosheets is a fascinating target because of their promising applications in electronics, membrane technology, catalysis, sensing, and energy technologies. Herein, a large‐area (square millimeters) and free‐standing 2D supramolecular polymer (2DSP) single‐layer sheet (0.7–0.9 nm in thickness), comprising triphenylene‐fused nickel bis(dithiolene) complexes has been readily prepared by using the Langmuir–Blodgett method. Such 2DSPs exhibit excellent electrocatalytic activities for hydrogen generation from water with a Tafel slope of 80.5 mV decade⁻¹ and an overpotential of 333 mV at 10 mA cm⁻², which are superior to that of recently reported carbon nanotube supported molecular catalysts and heteroatom‐doped graphene catalysts. This work is promising for the development of novel free‐standing organic 2D materials for energy technologies.     

Tuning Gold Nanoparticles with Chelating Ligands for Highly Efficient Electrocatalytic CO2 Reduction

Capped chelating organic molecules are presented as a design principle for tuning heterogeneous nanoparticles for electrochemical catalysis. Gold nanoparticles (AuNPs) functionalized with a chelating tetradentate porphyrin ligand show a 110‐fold enhancement compared to the oleylamine‐coated AuNP in current density for electrochemical reduction of CO₂ to CO in water at an overpotential of 340 mV with Faradaic efficiencies (FEs) of 93 %. These catalysts also show excellent stability without deactivation (<5 % productivity loss) within 72 hours of electrolysis. DFT calculation results further confirm the chelation effect in stabilizing molecule/NP interface and tailoring catalytic activity. This general approach is thus anticipated to be complementary to current NP catalyst design approaches.     

Supramolecular Enhancement of Electrochemical Nitrate Reduction Catalyzed by Cobalt Porphyrin Organic Cages for Ammonia Electrosynthesis in Water**

The electrochemical nitrate (NO₃⁻) reduction reaction (NO₃RR) to ammonia (NH₃) represents a sustainable approach for denitrification to balance global nitrogen cycles and an alternative to traditional thermal Haber-Bosch processes. Here, we present a supramolecular strategy for promoting NH₃ production in water from NO₃RR by integrating two-dimensional (2D) molecular cobalt porphyrin ( CoTPP ) units into a three-dimensional (3D) porous organic cage architecture. The porphyrin box CoPB-C8 enhances electrochemical active site exposure, facilitates substrate–catalyst interactions, and improves catalyst stability, leading to turnover numbers and frequencies for NH₃ production exceeding 200,000 and 56 s⁻¹, respectively. These values represent a 15-fold increase in NO₃RR activity and 200-mV improvement in overpotential for the 3D CoPB-C8 box structure compared to its 2D CoTPP counterpart. Synthetic tuning of peripheral alkyl substituents highlights the importance of supramolecular porosity and cavity size on electrochemical NO₃RR activity. These findings establish the incorporation of 2D molecular units into 3D confined space microenvironments as an effective supramolecular design strategy for enhancing electrocatalysis.     

Supramolecular Radical Anions Triggered by Bacteria In Situ for Selective Photothermal Therapy

A supramolecular complex that can be selectively reduced to radical anions in situ by facultative anaerobic bacteria is reported. To this end, a water‐soluble bifunctional monomer bearing perylene diimide was synthesized, and its supramolecular complex with cucurbit[7]uril was fabricated on the basis of host–guest complexation, which could be reduced to forming radical anions in the presence of E. coli . It was found that this supramolecular complex could display different ability of generating radical anions by facultative anaerobic and aerobic bacteria in terms of their various reductive abilities. The selective antibacterial activity of the supramolecular complex could be realized by the photothermal performance of the radical anions under near‐infrared irradiation. It is anticipated that this method may lead to a novel bacteria‐responsive photothermal therapy to regulate balance of bacterial flora.     

High‐Yield Electrosynthesis of Hydrogen Peroxide from Oxygen Reduction by Hierarchically Porous Carbon

H₂O₂ production by electroreduction of O₂ is an attractive alternative to the current anthraquinone process, which is highly desirable for chemical industries and environmental remediation. However, it remains a great challenge to develop cost‐effective electrocatalysts for H₂O₂ synthesis. Here, hierarchically porous carbon (HPC) was proposed for the electrosynthesis of H₂O₂ from O₂ reduction. It exhibited high activity for O₂ reduction and good H₂O₂ selectivity (95.0–70.2 %, most of them >90.0 % at pH 1–4 and >80.0 % at pH 7). High‐yield H₂O₂ generation has been achieved on HPC with H₂O₂ concentrations of 222.6–62.0 mmol L^?1 (2.5 h) and corresponding H₂O₂ production rates of 395.7–110.2 mmol h^?1 g^?1 at pH 1–7 and ?0.5 V. Moreover, HPC was energy‐efficient for H₂O₂ production with current efficiency of 81.8–70.8 %. The exceptional performance of HPC for electrosynthesis of H₂O₂ could be attributed to its high content of sp³‐C and defects, large surface area and fast mass transfer.     

Heat-Treated Aerogel as a Catalyst for the Oxygen Reduction Reaction

Aerogels are fascinating materials that can be used for a wide range of applications, one of which is electrocatalysis of the important oxygen reduction reaction. In their inorganic form, aerogels can have ultrahigh catalytic site density, high surface area, and tunable physical properties and chemical structures—important features in heterogeneous catalysis. Herein, we report on the synthesis and electrocatalytic properties of an iron–porphyrin aerogel. 5,10,15,20-(Tetra-4-aminophenyl)porphyrin (H₂TAPP) and Fe^II were used as building blocks of the aerogel, which was later heat-treated at 600 °C to enhance electronic conductivity and catalytic activity, while preserving its macrostructure. The resulting material has a very high concentration of atomically dispersed catalytic sites (9.7×10²⁰ sites g⁻¹) capable of catalyzing the oxygen reduction reaction in alkaline solution (E_onset=0.92 V vs. RHE, TOF=0.25 e⁻ site⁻¹ s⁻¹ at 0.80 V vs. RHE).     

From Supramolecular Species to Self‐Templated Porous Carbon and Metal‐Doped Carbon for Oxygen Reduction Reaction Catalysts

The preparation of carbon materials usually involves the decomposition of precursors and the reorganization of the as‐generated fragments. However, the cleavage of bonds and the simultaneous formation of new bonds at nearly the same positions prevents effective yet precise fabrication. Herein, a supramolecular precursor, cucurbit[6]uril, that contains multiple bonds with distinct bond strengths is proposed to decouple the twin problem of simultaneous bond cleavage and formation, allowing multistage transformations to hierarchical porous carbon and metal‐doped carbon in a single yet effective pyrolysis step without the need of a template or additional purification. As a proof‐of‐concept, the Fe‐doped carbon electrocatalysts realized a Pt/C‐like half‐wave potential of 0.869 V vs. RHE and small Tafel slope of 51.3 mV dec^?1 in oxygen reduction reaction.     

Spectroscopic Identification of Active Sites of Oxygen-Doped Carbon for Selective Oxygen Reduction to Hydrogen Peroxide

The electrochemical synthesis of hydrogen peroxide (H₂O₂) via a two-electron (2 e⁻) oxygen reduction reaction (ORR) process provides a promising alternative to replace the energy-intensive anthraquinone process. Herein, we develop a facile template-protected strategy to synthesize a highly active quinone-rich porous carbon catalyst for H₂O₂ electrochemical production. The optimized PCC₉₀₀ material exhibits remarkable activity and selectivity, of which the onset potential reaches 0.83 V vs. reversible hydrogen electrode in 0.1 M KOH and the H₂O₂ selectivity is over 95 % in a wide potential range. Comprehensive synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy combined with electrocatalytic characterizations reveals the positive correlation between quinone content and 2 e⁻ ORR performance. The effectiveness of chair-form quinone groups as the most efficient active sites is highlighted by the molecule-mimic strategy and theoretical analysis.     

Antimony Complexes for Electrocatalysis: Activity of a Main‐Group Element in Proton Reduction

Main‐group complexes are shown to be viable electrocatalysts for the H₂‐evolution reaction (HER) from acid. A series of antimony porphyrins with varying axial ligands were synthesized for electrocatalysis applications. The proton‐reduction catalytic properties of TPSb(OH)₂ (TP=5,10,15,20‐tetra(p ‐tolyl)porphyrin) with two axial hydroxy ligands were studied in detail, demonstrating catalytic H₂ production. Experiments, in conjunction with quantum chemistry calculations, show that the catalytic cycle is driven via the redox activity of both the porphyrin ligand and the Sb center. This study brings insight into main group catalysis and the role of redox‐active ligands during catalysis.     

Selective Oxidation of Toluene with Hydrogen Peroxide Catalyzed by V-Mo-based Catalyst

The selective catalytic oxidation of toluene with hydrogen peroxide over V-Mo-based catalysts under mild conditions was studied.The promotion effect of Mo on the catalysts was studied with V/Al2O3 and Mo/Al2O3 as reference samples.The catalysts were characterized by XRD,TPR,and XPS techniques.The results show that the addition of Mo to V/Al2O3 may change the distribution of V species on Al2O3 surface.Over V-Mo/Al2O3 catalyst,highly dispersed amorphous V species facilitates benzaldehyde formation,and crystalline V2O5 species increases the conversion of toluene but decreases the selectivity to benzaldehyde,while AlVMoO7 species favors both the conversion of toluene and the formation of cresols.The yield of benzaldehyde depends remarkably on the surface O/Al and Mo/V atomic ratios,and gets to a maximum value of 13.2% with a selectivity of 79.5% at an O/Al atomic ratio of 3.0 and Mo/V atomic ratio of 0.7.     

Multiple Hydrogen Bonding Enables the Self‐Healing of Sensors for Human–Machine Interactions

Despite its widespread use in signal collection, flexible sensors have been rarely used in human–machine interactions owing to its indistinguishable signal, poor reliability, and poor stability when inflicted with unavoidable scratches and/or mechanical cuts. A highly sensitive and self‐healing sensor enabled by multiple hydrogen bonding network and nanostructured conductive network is demonstrated. The nanostructured supramolecular sensor displays extremely fast (ca. 15 s) and repeatable self‐healing ability with high healing efficiency (93 % after the third healing process). It can precisely detect tiny human motions, demonstrating highly distinguishable and reliable signals even after cutting–healing and bending over 20 000 cycles. Furthermore, a human–machine interaction system is integrated to develop a facial expression control system and an electronic larynx, aiming to control the robot to assist the patient's daily life and help the mute to realize real‐time speaking.     

金属卟啉催化的过氧化氢选择氧化烃类反应机理研究

本文综合介绍了近年来采用过氧化氢为氧化剂,金属铁卟啉和锰卟啉模拟酶体系催化烯烃环氧化和烷烃氧化的反应机理。总结了采用不同手段促进过氧化氢的异裂,以有效形成金属卟啉活性中间体的反应过程。