Science China-Chemistry

Article	Citations
All at once arrangement of both oxygen atoms of dioxygen into aliphatic C(sp3)-C(sp3) bonds for hydroxyketone difunctionalization	456
Near-infrared H2O2 production via dual pathways of O2 reduction and H2O oxidation	384
Designing anticancer combretastatin A-4 analogues with aggregation-induced emission characteristics	222
Exfoliated metal oxide ultrathin nanosheets with supported Pd nanoparticles enabling the one-pot reaction of phenol into caprolactam	197
Highly selective synthesis and near-infrared photothermal response of heterometallic double trefoil knot and D-type [2]catenanes	113
Wide-pH-range adaptable ammonia electrosynthesis from nitrate on Cu-Pd interfaces	110
Constructing artificial mimic-enzyme catalysts for carbon dioxide electroreduction	107
Rational design and synthesis of advanced metal-organic frameworks for electrocatalytic water splitting	101
Reconfiguring perovskite interface via R4NBr addition reaction toward efficient and stable FAPbI3-based solar cells	99
Divergent asymmetric synthesis of azaarene-functionalized cyclic alcohols through stereocontrolled Beckwith-Enholm cyclizations	98
N-Heterocyclic carbene-stabilized platinum nanoparticles within a porphyrinic nanocage for selective photooxidation	94
Confined Mn2+ enables effective aerobic oxidation catalysis	94
Regulation of P450 TleB catalytic flow for the synthesis of sulfur-containing indole alkaloids by substrate structure-directed strategy and protein engineering	90
High-rate CH4-to-C2H6 photoconversion enabled by Au/ZnO porous nanosheets under oxygen-free system	90
Fluorination suppresses thermal quenching in perovskite QLEDs	86
Azobenzene-based ultrathin peptoid nanoribbons for the potential on highly efficient artificial light-harvesting	83
Phase-separated bienzyme compartmentalization as artificial intracellular membraneless organelles for cell repair	83
Organic white-light sources: multiscale construction of organic luminescent materials from molecular to macroscopic level	82
Visible-light-driven external-photocatalyst-free alkylative carboxylation of alkenes with CO2	80
From narrow-bandgap GeSe to wide-bandgap GeS solar cells	79
Molecular conformation-induced interfacial stress at the origin of the instability of organic transistors	76
Engineering multifunctional bioadhesive powders through dynamic metal-ligand coordination	73
Sulfanion-initiated open-vessel anionic ring-opening polymerization (AROP) of N-sulfonyl aziridines	73
Boosting multi-hole water oxidation catalysis on hematite photoanodes under low bias	72
A new path to highly conducting n-doped π-conjugated polymers	72

Al-containing Ge-rich IWV: rapid synthesis via interzeolite transformation and application in Baeyer-Villiger oxidation	70
A multi-parameter-induced activation of gas therapeutic platform to remarkably amplify photodynamic therapy efficacy	70
Highly dispersive tetrahedral vanadium species on pure silica ZSM-12 zeolite boosting the selective oxidation of cyclohexane into cyclohexanone	69
Constructing an efficient deep-blue TADF emitter by host-guest interactions towards solution-processed OLEDs with narrowband emission	65
Preface: Special issue in Honor of Professor Lixin Dai on the Occasion of His 100th Birthday	65
Room-temperature ferrimagnetism and size-modulated electronic structures in two-dimensional cluster-based metal-organic frameworks	63
C-H alkylation of pyridines with olefins catalyzed by imidazolin-2-iminato-ligated rare-earth alkyl complexes	62
Boosting propane dehydrogenation by gallium hydride species formed in situ	61
Developing silicon-based photocathodes for CO2 conversion	59
Regulating the electrolyte solvation structure by weakening the solvating power of solvents for stable lithium metal batteries	58
Efficient and stable organic solar cells enabled by a poly(carbazole phosphonic acid) hole transporter	58
Machine learning-assisted systematical polymerization planning: case studies on reversible-deactivation radical polymerization	57
CATase-immobilized hydrogel platform molded by photo-enzyme coupling polymerization for effectively preventing postoperative abdominal adhesion	56
Organocatalytic stereoselective cationic polymerization of vinyl ethers by employing a confined brønsted acid as the catalyst	56
Employ ionic liquid to stabilize black-phase formamidinium perovskites	55
Mn-based cathode materials for rechargeable batteries	55
De novo design of transmembrane nanopores	54
Functional carbon materials addressing dendrite problems in metal batteries: surface chemistry, multi-dimensional structure engineering, and defects	54
Porous metal-organic cage-based membranes	53
A molecular brake hoop for the motion of metal atoms inside fullerene cage	52
The induction of PANoptosis in KRAS-mutant pancreatic ductal adenocarcinoma cells by a multispecific platinum complex	51
Persistent radical anion of perylene dianhydride: an emerging metal-free photocatalyst for near-infrared photocontrolled RAFT polymerization	51
Instantaneous visual imaging of latent fingerprints in water	50
Brightening room-temperature phosphorescence in solution	50
Record-high near-band-edge optical nonlinearities and two-level model correction of poled polymers by spectroscopic electromodulation and ellipsometry	50
The chlorine evolution reaction promoted by organocatalysts with amide functional groups	50
A lysosomal-targeted Pt(II) metallacycle for NIR-II fluorescence imaging guided highly efficient tumor immunogenic cell death	49
Thioredoxin pathway regulated live-cell synthesis of CdSe quantum dots in Saccharomyces cerevisiae	48
Prospects and challenges in electrochemical nitrogen activation for ammonia synthesis	48
Attaching CF3 groups to organic molecules using trifluoroacetates via ion-shielding photoelectrocatalysis	48
Interwoven grain boundary makes homoporous and crystalline polymer membrane with high mechanical stability	48
Tandem hydroformylation/hydrogenation of olefins to alcohols using atomically dispersed bifunctional catalysts	47
Recent progress in sulfonyl fluoride synthesis via the radical sulfur dioxide insertion and fluorination strategy	47
Regioselective C-C bond cleavage/aminocarbonylation cascade under copper catalysis	47
Novel photoresponsive dinuclear nickel catalysts for ethylene (co)polymerization	44
The structure-performance correlation of bulk-heterojunction organic solar cells with multi-length-scale morphology	44
In-situ generation of poly(quinolizine)s via catalyst-free polyannulations of activated diyne and pyridines	44
Palladium-catalyzed SN2 glycosylation of phenols	43
Organoboron chemistry towards controlled and precise polymer synthesis	42
Lanthanide-oxo clusters for efficient catalytic reduction of carboxamides	41
Tuning the local coordination environment of silver(I) coordination networks with counterions for enhanced electrocatalytic CO2 reduction	41
pH-Dependent binding energy-induced inflection-point behaviors for pH-universal hydrogen oxidation reaction	41
Liquid crystal-based optical aptasensor for the sensitive and selective detection of Gram-negative bacteria	40
Breakthrough in construction of oxygen-independent photosensitizer for type III photodynamic therapy	40
Recent progress in carbene-catalyzed fluoroalkylation	39
Upcycling of polyphenylene oxide into 2,6-dimethyl aniline via depolymerization and amination over a Pt/CeO2 catalyst	39
Nickel-catalyzed enantioselective reductive amination of benzylic ketones in alcohols	39
Microfluidic generation of barcodes with in situ synthesized perovskite quantum dot encapsulation	39
Janus mesoporous nanoparticles enable building biological logic systems	38
Phase-mediated controllable intramolecular and intermolecular photocycloadditions assisted by supramolecular templates	37

Offsetting the thermal expansion mismatch: a new way to high-performance solid oxide fuel cell cathodes	37
Construction of N-doped copper metal–organic frameworks for promoting photocatalytic carbon dioxide reduction to ethylene	37
An electron-transfer [Fe2Co2] square complex exhibiting unprecedented wide room-temperature hysteresis	36
Chemoselective desulfurization-fluorination/bromination of carbonofluoridothioates for the O-trifluoromethylation and O-bromodifluoromethylation of alcohols	36
Leaf-inspired design of mesoporous Sb2S3/N-doped Ti3C2Tx composite towards fast sodium storage	35
Efficient green OLEDs achieved by a terbium(III) complex with photoluminescent quantum yield close to 100%	35
An automated nucleic acid detection platform using digital microfluidics with an optimized Cas12a system	35
Flour-derived borocarbonitride enriched with boron–oxygen species for the oxidative dehydrogenation of propane to olefins	35
New electrocatalysts and mechanisms pave the way to urea oxidation with superior activities and stability	35
Biological membrane derived nanomedicines for cancer therapy	35
Probing molecular orientation at bulk heterojunctions by polarization-selective transient absorption spectroscopy	35
The chemistry and physics of organic—inorganic hybrid perovskite quantum wells	34
Chiroluminophores based on non-conjugated benzenes	34
Metal-free synthesis of nitriles from aldehydes and ammonium by visible-light photocatalysis	34
Modulation of terminal alkyl chain length enables over 15% efficiency in small-molecule organic solar cells	34
Engineering intermolecular charge transfer in chiral organometallic crystals by rational doping for high-contrast CPL switches	34
A topological polymer network with Cu(II)-coordinated reversible imidazole-urea locked unit constructs an ultra-strong self-healing elastomer	34
In-situ formation of a new cation renders perovskite solar modules with a record efficiency and long-term stability	34
Recent advances in Raman spectroelectrochemistry on single-crystal surfaces	33
Active sites and reaction mechanisms of COx hydrogenation on zinc-based mixed oxide catalysts	33
Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with β-trifluoromethyl-substituted alkenyl heteroarenes	33
Steering structural mesoporosity and working microenvironment of Fe-N-C catalysts for boosting cathodic mass transport of zinc-air batteries	32
High-temperature dielectric polymer composite for high power energy storage applications	32
A robust ethane-trapping metal-organic framework for efficient purification of ethylene	32
CAr–Br bond cleavage via cooperative EnT/NHC catalysis: mild access to indolines	32
Molecule configurations modulate packing array and charge transfer in cocrystal engineering	32
Lipase-activated glycopeptide nano-assemblies as an antibiotic nano-adjuvant to inhibit Pseudomonas aeruginosa biofilm and enhance antibacterial activity	32
Carbene-catalyzed enantioselective seleno-Michael addition as access to antimicrobial active Se-containing heterocycles	32
Bimolecular reduction of carbon dioxide: double synthons for alkynes trifunctionalization	31
Unraveling light localization in quasi-periodic photonic lattices	31
A combinatorial synthesis method for identification of orally bioavailable cyclic peptide	31
Pressure effects on metal/covalent-organic frameworks: structural and optical properties	31
A highly reduced Mo74 polyoxometalate featuring high proton conductivity accessed by building block strategy	30
Illuminating spin-crossover octanuclear metal-organic cages	30
An unprecedented synthesis of axially chiral biaryls by rearrangement and aromatization of carbocations with central-to-axial conversion of chirality	30
The centrosymmetric to non-centrosymmetric transformation induced by alkaline-earth cations producing infrared nonlinear optical AeMn6Ga6S16 (Ae = Ca, Sr)	30
Electrochemically promoted N-heterocyclic carbene polymer-catalyzed cycloaddition of aldehyde with isocyanide acetate	30
Visualizing Aβ deposits in live young AD model mice with a simple red/near-infrared-fluorescent AIEgen	30
Bacterial microcompartment-mimicking Pickering emulsion droplets for detoxification of chemical threats under sweet conditions	30
Recent progress in diagnostic imaging and therapeutics of osteosarcoma based on multifunctional nanoparticles	30
Lighting up plants with near-infrared fluorescence probes	30
Multi-stimuli-responsive aggregation-induced emission copper iodide cluster	30
Continuous Fe3+ releasing enabled complete reconstruction of Ni-based MOF for promoted water oxidation in industrial alkali	30
Selenium vacancies regulate d-band centers in Ni3Se4 toward paired electrolysis in anion-exchange membrane electrolyzers for upgrading N-containing compounds	30
Enantioselective synthesis of tetrasubstituted allenes via addition/arylation tandem reaction of 2-activated 1,3-enynes	29
Face-centered cubic structured RuCu hollow urchin-like nanospheres enable remarkable hydrogen evolution catalysis	29
Polyoxometalate-based flexible conductive materials with superionic conductivity	29
Modulating the electrode-electrolyte interface enables switchable selectivity in electrocatalytic furfural reduction	29
Recent advances in the synthesis of discrete oligomers and polymers: chemistry, strategy and technology	29
Electrostatic interaction-mediated 1:1 complexes for high-contrast mitochondrial-targeted phosphorescence bioimaging	29
Evoking immune system to potentiate nanocatalytic therapy through activation of cGAS-STING pathway	29
Multi-twinned gold nanoparticles with tensile surface steps for efficient electrocatalytic CO2 reduction	29
How temperature and hydrostatic pressure impact organic room temperature phosphorescence from H-aggregation of planar triarylboranes and the application in bioimaging	29
Hydrogen bond-induced elastic polyzwitterion electrolytes constructed by mussel-inspired autopolymerization for zinc-ion battery	29
Strengthening and toughening styrene-butadiene rubber by mechanically interlocked cross-links	29
FeOOH photo-deposited perylene linear polymer with accelerated charge separation for photocatalytic overall water splitting	28
Activity promotion of Rh1Cax/Al2O3 single-atom catalyst in 1-octene hydroformylation: a volcano curve exists between Ca adding ratio and catalytic activity	28
Nickel-catalyzed cross-electrophile C-Ge coupling of benzyl pivalates and chlorogermanes	28
Sequence structure controllable polymerization-induced self-assembly	28
Hierarchical ZrO2@N-doped carbon nano-networks anchored ultrafine Pd nanoparticles for highly efficient catalytic hydrogenation	28
Visible light-mediated NHCs and photoredox co-catalyzed radical 1,2-dicarbonylation of alkenes for 1,4-diketones	28
NIR photosensitizers activated by γ-glutamyl transpeptidase for precise tumor fluorescence imaging and photodynamic therapy	28
Molecular doping for persistent afterglow	28
Self-healable and mechanically robust supramolecular-covalent poly(oxime-urethane) elastomers with information encryption via hydrogen bonds and coordinate interactions	27
Molecular mechanism of crystal nucleation from solution	27
Achieving improved stability and minimal non-radiative recombination loss for over 18% binary organic photovoltaics via versatile interfacial regulation strategy	27
Metal cluster-regulated switching of reactive oxygen species within ionic porphyrin cages for efficient chemical warfare agent detoxification	27
Host defense peptide-mimicking peptide polymer-based antibacterial hydrogel enables efficient healing of MRSA-infected wounds	27
A charge-assisted hydrogen-bonded organic framework with polar porosities for selective separation of o-xylene from C8H10 aromatic isomers	27
Donor strategy for promoting nonradiative decay to achieve an efficient photothermal therapy for treating cancer	27
Cobalt-catalyzed highly α-selective hydrostannylation of terminal alkynes	27
Printable and stable all-polymer solar cells based on non-conjugated polymer acceptors with excellent mechanical robustness	27
Supramolecular systems for bioapplications: recent research progress in China	27
Split crRNA-motivated amplification-free RNA testing with CRISPR–Cas12a	26
Cation-π and electrostatic interactions co-driven assembly of two-dimensional heteropore supramolecular polymers with rapid iodine capture capability	26
Bright-white hydrogels for on-demand passive cooling	26
Room temperature phosphorescence achieved by aromatic/perfluoroaromatic interactions	26
Integrated interface between composite electrolyte and cathode with low resistance enables ultra-long cycle-lifetime in solid-state lithium-metal batteries	26
A low-cost wide bandgap polymer based on carboxylate substituted thiazole enables efficient organic solar cells with remarkable batch-to-batch reproducibility	26
Structural tailoring of covalent organic frameworks with steric effects	26

“In-N-out” design enabling high-content triethyl phosphate-based non-flammable and high-conductivity electrolytes for lithium-ion batteries	26
Recent progress in all-inorganic tin-based perovskite solar cells: a review	26
Improvement of charge-transfer kinetics via MXene and cobalt containing polyoxometalate loading on CdS for photocatalytic hydrogen production	26
Regulation of the activity, selectivity, and durability of Cu-based electrocatalysts for CO2 reduction	26
Palladium-catalyzed enantioselective carbonylation reactions	26
Catalyst-controlled regiodivergent 1,2-difunctionalization of alkenes with two carbon-based electrophiles	26
Chemically recyclable copolyesters from bio-renewable monomers: controlled synthesis and composition-dependent applicable properties	26
A bifunctional wood membrane modified by MoS2/covalent organic framework heterojunctions for effective solar-driven water evaporation and contaminant degradation	25
Shapeable carbon fiber networks with hierarchical porous structure for high-performance Zn-I2 batteries	25
Polymerized A-DA’D-A type small-molecule acceptors for high performance all-polymer solar cells: progress and perspective	25
Inductive effect of Ti-doping in Fe2O3 enhances the photoelectrochemical water oxidation	25
Metal-organic frameworks with dinuclear metal centers for synergistically boosting CO2 photoreduction	25
Efficient nitrate electroreduction over Mn-doped Cu catalyst via regulating N-containing intermediates adsorption configuration	25
Porous organic polymers: a progress report in China	25
Operando reconstruction towards stable CuI nanodots with favorable facets for selective CO2 electroreduction to C2H4	25
High-efficiency organic solar cells processed from a halogen-free solvent system	25
Covalent organic frameworks catalyzed by organic Lewis acid	25
Cerium-based nanomaterials for photo/electrocatalysis	25
Narrow bandgap molecular dyads Incorporating Y-series acceptor backbones for efficient single-molecular organic solar cells	25
Industry-compatible covalent organic frameworks for green chemical engineering	25
Recent development in electrode design for wide-temperature supercapacitors	24
Dative B-N bonds weaven toward two-dimensional purely organic materials for single crystals	24
Deciphering fungal metabolon coupling tandem inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids	24
Cocatalysts in photocatalytic methane conversion: recent achievements and prospects	24
Tailor-made high elasticity and low-hysteresis hydrogels based on asymmetric H-bonding crosslinking for wearable applications	24
NAD(P)H inspired CO2 reduction and beyond	24
Applications of in-situ solid-state nuclear magnetic resonance in methanol to olefins reaction	24
Unraveling the impacts of intermolecular interaction on morphology evolution for highly efficient organic solar cells and modules	24
Cyano migration-mediated radical-polar crossover cyclopropanation	24
InNi alloy-induced interface effect promoting the parallel electron transfer: improved photothermal catalytic CO2 hydrogenation	24
Covalent organic framework nanoparticles for anti-tumor gene therapy	24
Physarum polycephalum-inspired adaptive optimization design of artificial microtubular networks	24
De novo synthesis of atropisomeric benzofurans via Cu/SPDO complex catalyzed asymmetric formal [3 + 2] annulation	24
Precise gradient separation of nanoparticles using reduced graphene oxide-polyoxomolybdate membranes	24
Covalent organic frameworks with asymmetric unprotonated/protonated structures for efficient photocatalytic hydrogen evolution	24
Enhancing solid-state lithium metal battery performance via indium-based modification of electrolytes and lithium metal surfaces: mechanistic insights and optimization	24
Hierarchical self-assembly of crown ether based metal-carbene cages into multiple stimuli-responsive cross-linked supramolecular metallogel	24
Two-dimensional material-based virus detection	23
Photocatalytic vinyl radical-mediated multicomponent 1,4-/1,8-carboimination across alkynes and olefins/(hetero)arenes	23
In situ/operando characterization techniques for electrochemical CO2 reduction	23
In-situ ECSTM investigation of H2O2 production in cobalt—porphyrin-catalyzed oxygen reduction reaction	23
S-, P-stabilized bromoallenes for modular allenylborylation of alkenes	23
Coordination cage with structural “defects” and open metal sites catalyzes selective oxidation of primary alcohols	23
Sulfur-induced dynamic reconstruction of iron-nitrogen species for highly active neutral oxygen reduction reactions	23
Refining acceptor aggregation in nonfullerene organic solar cells to achieve high efficiency and superior thermal stability	23
The d-orbital coupling modulation of CuNi alloy for acetonitrile electrochemical reduction and in-situ hydrogenation behavior characterization	23
High-performance all-polymer solar cells enabled by a novel low bandgap non-fully conjugated polymer acceptor	23
Promoting nitric oxide electroreduction to ammonia over electron-rich Cu modulated by Ru doping	23
C-F bond activation under transition-metal-free conditions	23
Donor-acceptor 2D covalent organic frameworks for efficient heterogeneous photocatalytic α-oxyamination	23
Cucurbit[8]uril-mediated multi-color fluorescence system for time-dependent information encryption	22
Multifunctional design of single-atom catalysts for multistep reactions	22
Weakly-solvating electrolytes enable ultralow-temperature (−80 °C) and high-power CFx/Li primary batteries	22
BaYOBO3: A deep-ultraviolet rare-earth oxy-borate with a large second harmonic generation response	22
Memorable full-color circularly polarized luminescence from chiral co-assembled polymer films enabled by multipath transfer	22
Practicing the concept of “structuring” processing in the manufacture of polymer films	22
Chiral Brønsted acid-catalyzed asymmetric intermolecular [4 + 2] annulation of ynamides with para-quinone methides	22
Metalphthalocyanine frameworks grown on TiO2 nanotubes for synergistically and efficiently electrocatalyzing urea production from CO2 and nitrate	22
Post-synthetic metalation of organic cage for enhanced porosity and catalytic performance	22
High-gain signal-on PEDOT:PSS organic photoelectrochemical transistor biosensing modulated by a MXene/MOFs/NiO Schottky heterojunction	22
Visible-light-induced, autopromoted nickel-catalyzed three-component arylsulfonation of 1,3-enynes and mechanistic insights	22
Electrochemical conversion of furfural to furoic acid: a more stable, efficient and energy-saving system	22
Clustering-triggered phosphorescence of nonconventional luminophores	22
Highly stable Eu-coordination polymer exhibiting the highest quantum yield	22
Recent advances in room-temperature phosphorescent materials by manipulating intermolecular interactions	22
Reduction of unactivated alkyl chlorides enabled by light-induced single electron transfer	21
Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?	21
Copper-catalyzed enantioselective desymmetrizing C(sp2)–H functionalization of azide-ynamides via α-imino copper carbenes	21
Visible-light-driven thio-carboxylation of alkynes with CO2: facile synthesis of thiochromones	21
Aggregation-induced dual-color luminogen with enhanced chiroptical property	21
Immunologically effective poly(D-lactic acid) nanoparticle enhances anticancer immune response	21
Highly efficient room temperature phosphorescent liquid crystalline polymer optical waveguides for advanced optoelectronics	21
Emerging technologies for uranium extraction from seawater	21
Biomedical polymers: synthesis, properties, and applications	21
Novel boron- and sulfur-doped polycyclic aromatic hydrocarbon as multiple resonance emitter for ultrapure blue thermally activated delayed fluorescence polymers	21
Azocalixarenes: a scaffold of universal excipients with high efficiency	21
Two polyoxovanadoborates with over 100 nuclei assembled from a {V14Co12B72} cluster	21
Circularly polarized phosphorescence and photon transport of micro/nanocrystals of ruthenium and iridium complexes with chiral anions	21
GSH-induced chemotaxis nanomotors for cancer treatment by ferroptosis strategy	21
Extended light absorption and accelerated charge migration in ultrathin twisted carbon nitride nanoplates for efficient solar hydrogen production	20
Advances in self-assembly-based circularly polarized luminescent materials	20
Dynamic polymers based on oxime-urethane chemistry: design, performances, and applications	20
Mechanochemistry of cyclobutanes	20
Stable perovskite solar cells with 23.12% efficiency and area over 1 cm2 by an all-in-one strategy	20
Upgrading ethylene via renewable energy-driven electrocatalysis	20
Review on birefringence in borates based on birefringence-active functional groups and arrangements	20
Erratum to: Science China Chemistry Volume 65 Number 7, July 2022	20
Electrochemical impedance spectroscopy analysis to accelerate electrocatalytic system innovation	20
All-in-one strategy: overcome the challenges in the device enlargement of perovskite solar cells	20
Theranostic nanosystem mediating cascade catalytic reactions for effective immunotherapy of highly immunosuppressive and poorly penetrable pancreatic tumor	20
Crystal-phase-controlled PtSn intermetallic nanowires for efficient methanol oxidation	20
Lighting up aggregate emission of perylene diimide by leveraging polymerization-mediated through-space charge transfer and π-π stacking	20
Size-selective hybridization chain reaction for accurate signal amplification in living cancer cells	20
Cleavable Cys labeling directed Lys site-selective stapling and single-site modification	20
Origin and effect of surface oxygen-containing species on electrochemical CO or CO2 reduction reactions	20