The electrochemical two-electron oxygen reduction reaction (2e(-)-ORR) offers a sustainable route to H2O2 production, yet the pursuit of efficient and durable catalysts under acidic conditions remains challenging. Herein, a defect-rich porous carbon catalyst with encapsulated Co nanoparticles (NPs), denoted as PZC, is fabricated by pyrolyzing ZIF-67 synthesized with coordination modification by polyvinyl pyrrolidone (PVP). PVP coordination simultaneously enhances carbon defect density, surface area, and mesoporosity, while stabilizing Co NPs within the carbon framework. The resulting PZC exhibits a near-theoretical onset potential of 0.693 V vs. RHE and 91.5-97.0% H2O2 selectivity over a wide potential window in 0.1 M HClO4. Mechanistic studies, combining in-situ ATR-SEIRAS, poisoning experiments, and DFT calculations, reveal a synergistic effect between zigzag carbon defects and encapsulated Co NPs in optimizing *OOH adsorption energy, thus accelerating kinetics and suppressing H2O2 decomposition. In an H-cell, PZC delivers an outstanding H2O2 production rate of 5.74 mol g(-1) h(-1) and demonstrates long-term stability over 140 h. Coupling PZC-driven H2O2 electrosynthesis with titanium silicalite-1 (TS-1)-catalyzed propylene oxidation enables in situ production of 1,2-propylene glycol with >80% Faradaic efficiency. This work not only establishes a design principle based on the synergy between carbon defects and Co NPs for high-performance 2e(-)-ORR catalysts under acidic conditions, but also successfully demonstrates their integration into value-added chemical synthesis.

Methanol is an attractive liquid feedstock for sustainable H2 production due to its high hydrogen storage density and favorable handling properties, yet conventional routes typically involve harsh conditions or noble-metal catalysts. Here, we present a catalyst-free microdroplet strategy for efficient H2 production from aqueous methanol under mild conditions, achieving an evolution rate of 968.1 μmol h-1 in an enlarged 3.5 L reactor using seawater as the water source. This performance outperforms most reported photocatalytic methanol dehydrogenation systems, with formaldehyde as the dominant liquid-phase product. Mechanistic insights from electron paramagnetic resonance, isotopic labeling, mass spectrometry, and theoretical calculations provide a plausible explanation for methanol dehydrogenation in water microdroplets, driven by hydroxyl radicals (•OH) generated at the gas-liquid interface. This approach was successfully validated in both scaled-up experiments and in additional hydrogen storage media (formaldehyde, ammonia, ethylene glycol, formic acid, and ethanol), suggesting its potential scalability and substrate generality for an H2 production platform.

Crystal plane engineering is a powerful tool to optimize catalytic efficiency in heterogeneous catalysis. However, there is a surprising dearth in the exploration of the support plane effect on glycerol hydrogenolysis to 1,3-propanediol (1,3-PDO). In this work, we synthesized prism-shaped rutile TiO2 nanorods (RTNR-T) with tunable {110}/{111} exposure ratios by varying the hydrothermal temperature. The proportion of the {110} planes is identified to exhibit a volcano-like relationship with the hydrothermal temperature. The concentrations of oxygen vacancies and Ti3+ sites on both the RTNR-T nanorods and Pt-WOx/RTNR-T catalysts are positively correlated with the proportion of the {110} planes. Coherently, the Pt dispersion and surface acidity on the catalysts are parallel to the proportion of the {110} planes, attributable to the high defect density that facilitates the anchorage of Pt and promotes WOx-support interaction. In glycerol hydrogenolysis, the Pt-WOx/RTNR-453 catalyst with the highest proportion of the {110} planes displayed the best catalytic performance, with glycerol conversion and 1,3-PDO selectivity of 96.7% and 60.6%, respectively, affording an outstanding 1,3-PDO yield of 58.6% and excellent recyclability. Density functional theory calculations demonstrated that the presence of defects markedly reduced the dissociation and diffusion barriers, which greatly boosts hydrogen spillover to WOx for in-situ Brönsted acid site generation and oxocarbenium intermediate hydrogenation. This work offers a robust design principle based on the crystal plane-defect-activity correlation for high-performance glycerol hydrogenolysis catalysts.

Methanol is an attractive liquid feedstock for sustainable H2 production due to its high hydrogen storage density and favorable handling properties, yet conventional routes typically involve harsh conditions or noble-metal catalysts. Here, we present a catalyst-free microdroplet strategy for efficient H2 production from aqueous methanol under mild conditions, achieving an evolution rate of 968.1 mu mol h-1 in an enlarged 3.5 L reactor using seawater as the water source. This performance outperforms most reported photocatalytic methanol dehydrogenation systems, with formaldehyde as the dominant liquid-phase product. Mechanistic insights from electron paramagnetic resonance, isotopic labeling, mass spectrometry, and theoretical calculations provide a plausible explanation for methanol dehydrogenation in water microdroplets, driven by hydroxyl radicals (center dot OH) generated at the gas-liquid interface. This approach was successfully validated in both scaled-up experiments and in additional hydrogen storage media (formaldehyde, ammonia, ethylene glycol, formic acid, and ethanol), suggesting its potential scalability and substrate generality for an H2 production platform.

Abstract Conventional industrial technologies for cyclohexanone production, a key precursor to ε-caprolactam, primarily cyclohexane oxidation (CHA-Ox) and cyclohexene hydration (CHE-Hydr), are constrained by an inherent trade-off between conversion and selectivity. This leads to low carbon atom utilization or high energy intensity, together with substantial environmental burdens. The cyclohexene esterification–reduction (CHE-ER) route, first proposed by the Research Institute of Petroleum Processing (RIPP), delivers exceptional conversion and selectivity and therefore offers a promising platform for next-generation cyclohexanone production. However, the central challenge has been to translate the intrinsic advantages of this chemistry into a process that is simultaneously economically competitive and environmentally sustainable. Here we report a set of critical chemical engineering innovations that streamline process design and substantially reduce energy consumption. By leveraging the inertness of cyclohexane during cyclohexene esterification, we designed a new extraction system that selectively separates benzene from its partial hydrogenation products. We further implemented a hybrid reactor configuration integrating a fixed-bed reactor with a catalytic reactive distillation reactor for cyclohexene esterification with acetic acid. In addition, we identified and strategically harnessed the beneficial roles of cyclohexane in facilitating reaction heat dissipation and excess acetic acid separation. These innovations have been successfully deployed in a 400 kt yr–1-capacity industrial plant for cyclohexanone production via the CHE-ER route, affording nearly complete cyclohexene conversion and cyclohexyl acetate selectivity above 99.0%. This work establishes a new-generation of industrial technology for cyclohexanone production that maximizes economic benefit, while minimizes energy demand and environmental impacts associated with conventional processes.

The electrocatalytic reduction of O2 via two-electron reaction (2e-ORR) to H2O2 represents a promising alternative to the current anthraquinone process, since it is advantageous in the sustainable and decentralized production of H2O2. Herein, we report the development of oxygen and nitrogen-rich few-layered graphene-like materials (ms-dcda) by the one-step carbonization of biomass-sourced monosaccharides (D-glucose, D-fructose, D-galactose, D-ribose, D-xylose, L-arabinose, and D-mannose) with the aid of dicyandiamide for electrochemical O2 reduction to H2O2. The ms-dcda materials were porous and possessed wrinkled morphology typical of graphene nanosheets. In H2O2 production via 2e-ORR in an acidic electrolyte, these ms-dcda materials were all active and stable catalysts, among which glu-dcda derived from D-glucose and dicyandiamide displayed the lowest onset potential of 0.553 V and the highest selectivity of up to 91.6%. The catalyst was also highly stable in chronoamperometric tests. Selective chemical titration of the C–OH and C=O groups revealed that the latter is far more active and selective than the former in 2e-ORR. Moreover, a positive correlation between the contents of C=O and pyrrolic N and the H2O2 partial current suggests that the pyrrolic N group also contributes to 2e-ORR. This work affords a facile strategy for the sustainable fabrication of metal-free carbon-based catalysts efficient for H2O2 electrosynthesis.

The photocatalytic oxidation of methane to methanol using molecule oxygen directly is an attractive catalytic reaction,but designing catalysts to avoid over-oxidation remains a significant challenge.Herein,Cu single-atom anchored on the defective carbon nitride structure(Cu SA/Def-CN)is de-signed for selective photocatalytic oxidation of methane into methanol using O2 under mild condi-tions.The Cu SA/Def-CN catalyst exhibits a high methanol selectivity of 92.8％under optimized conditions.Mechanistic studies reveal a synergistic effect between Def-CN and Cu SA,where Def-CN is responsible for the in-situ generation of hydrogen peroxide,which is subsequently decomposed by the Cu SA sites to produce·OH radicals that play a key role in the rate-determining step of me-thane activation to form methanol.Additionally,the presence of Cu SA not only enhances the elec-tron-hole separation efficiency and improves the transfer of the photo-generated charges,but also increases the number of active sites for methane adsorption and activation.These insights provide valuable guidance for designing efficient catalysts for the highly selective photocatalytic oxidation of methane to methanol.

Electrocatalytic two-electron O2 reduction reaction (2e- -ORR) is an inexpensive, clean, and safe route for H2O2 production. The elucidation of the active site is essential for the rational design of efficient 2e- -ORR catalyst. Herein, nitrogen and oxygen dual-doped carbon electrocatalysts (p-SC-dicy) were synthesized using saccharides as the carbon sources, and dicyandiamide (dicy) as the precursor to the self-sacrificial template and the nitrogen source. At identical polymerization degree, alpha-glycosidic bond-linked saccharides gave rise to higher porosity and heteroatom doping levels than beta-glycosidic bond-linked ones. In 2e- -ORR, the p-SC-dicy catalysts prepared from alpha-glycosidic bond-linked maltose and starch outperformed those from beta-glycosidic bond-linked cellobiose and cellulose. Moreover, at identical glycosidic bond type, the catalytic activity is positively correlated with the polymerization degree for alpha-glycosidic bond-linked saccharides, while negatively for beta-glycosidic bond-linked ones. Among them, p-st-dicy prepared from starch exhibited the best 2e- -ORR activity, selectivity, and stability. A combination of surface analysis, chemical titration of the oxygen- and the nitrogen-containing groups, with the latter being conducted for the first time, and density function theory (DFT) calculations identified that the carbon atom adjacent to the aldehyde group and the amino group is the most effective active site for 2e- -ORR.

Driven by advances in the biodiesel industry,converting glycerol,the major byproduct,into valuable chemicals such as 1,3-propanediol(1,3-PDO)via selective hydrogenolysis has emerged as an important research topic.However,there is a dearth in the study of the effect of the bi-phase support on the catalytic performance of the Pt-WOx-based catalyst in glycerol hydrogenolysis.In this contribution,we synthesized bi-phase TiO2(bp-TiO2)materials with varying rutile to anatase phase ratios using a coordination-mediated self-assembly method by adjusting the amount of HCl added.These materials were then used as supports for Pt-WOx catalysts to investigate the effect of crystal phase composition of the support on glyc-erol hydrogenolysis to 1,3-PDO.The Pt-WOx/bp-TiO2 catalysts were systematically characterized by techniques including X-ray diffraction(XRD),Raman spectrometry,N2 physisorption,CO pulsed adsorption,transmission electron microscopy(TEM),pyridine adsorption-Fourier transform infrared spectrometry(Py-IR),temperature-programmed desorption of NH3(NH3-TPD),and H2 chemisorption,focusing on the phase composition,distribution and dispersion of the Pt and WOx species,acidic property,and ability of hydrogen spillover.The XRD results revealed that with the increase in the HCl dosage,the content of the rutile phase in the support increased first,and then decreased,reaching a maximum of 29％.The TEM and X-ray photoelectron spectroscopy(XPS)results disclosed that the Pt particles and WOx species were inclined to distribute on the rutile phase.The H2 chemisorption results demonstrated that the introduction of the rutile phase greatly enhanced the hydrogen spillover ability of the catalysts.In glycerol hydrogenolysis,it is identified that the glycerol conversion generally improved with the increase in the content of the rutile phase in the support,while the selectivity to 1,3-PDO remained virtu-ally constant at around 60％.Over the Pt-WOx/bp-TiO2(4)catalyst with the highest rutile content of 29％,the yield of 1,3-PDO reached the highest value of 30.3％.This catalyst also displayed good stability.It is plausible that the preferential distribution of the Pt and WOx species on the rutile surface is conducive to the formation of more Pt-WOx interfaces,which greatly enhances hydrogen spillover and thus boosts the yield of 1,3-PDO.This work elucidates the important role of the phase composition of bi-phase TiO2 support on the catalytic performance of the Pt-WOx-based catalyst in glycerol selective hydrogenolysis,which opens up new avenue for the design of high-performance glycerol hydrogenolysis catalysts by means of engineering the phase composition of the support.

Photocatalytic oxidation of methane to methanol oxygenates (CH3OH and CH3OOH) under mild conditions represents a promising approach for methane valorization, yet achieving both high efficiency and high selectivity remains a significant challenge. Herein, a defect-engineered spatial coupling strategy is devised to construct a heterojunction photocatalyst (Def-CuCN/NU) by integrating copper single atoms (Cu SA) anchored on polymeric carbon nitride (CN) into the defective NH2-UiO-66 (Def-NU). The defective MOFs with porous structure and abundant active sites serve as microreactors that enhance methane adsorption and promote methanol desorption, thus promoting the reaction and minimizing the contact of methanol with ·OH radicals and effectively suppressing overoxidation. Additionally, the heterojunction formed between CuCN and Def-NU accelerates charge separation and transport, which renders efficient photocatalytic conversion of methane to methanol oxygenates. Notably, the Def-CuCN/NU catalyst affords a high production rate of 1718 µmol g-1 h-1 for methanol oxygenates under full-spectrum light irradiation at a remarkable selectivity of 96.5%. This study presents the first demonstration of employing defect-engineered MOFs-based heterojunction photocatalysts for the regulation of the reaction pathway to enable highly selective photocatalytic oxidation of CH4.

By utilizing greenhouse gas CO2 and renewable energy-sourced H2 to produce methanol, the “methanol economy” can replace fossil fuels and H2 as the energy storage medium, which not only reduces CO2 emissions, but also mitigates the energy shortage issue. However, the traditional Cu-based catalysts for CO2-to-methanol conversion suffer from low activity at low temperature and high vulnerability to sintering and deactivation. In this contribution, rapidly quenched skeletal Cu catalysts (RQ Cu) are prepared by leaching the RQ Cu–Al alloy with NaOH aqueous solutions of different concentrations. It is found that high NaOH concentration of 10 wt% favors the preparation of the RQ Cu-10 catalyst with higher porosity, lower residual Al content, and larger active Cu surface area (SCu) than the RQ Cu-3 catalyst leached with 3 wt% of NaOH solution. However, in aqueous-phase CO2 hydrogenation at 473 K and 4.0 MPa, the CO2 conversion over the RQ Cu-3 catalyst is more than two times greater than that over the RQ Cu-10 catalyst, and the selectivity and productivity of methanol are 1.20 and 2.69 times of the corresponding values over the RQ Cu-10 catalyst. At 5.0 MPa, the selectivity and productivity of methanol are further boosted to 97.9% and 1.329 mmol gCu–1 h–1 on the RQ Cu-3 catalyst. It is identified that the SCu of the RQ Cu-3 catalyst is well preserved after reaction, while dramatic growth of the Cu crystallites occurs for the RQ Cu-10 catalyst. The better catalytic performance and stability of the RQ Cu-3 catalyst are tentatively attributed to the presence of more residual Al species by using NaOH solution with lower concentration for Al leaching, which acts as the dispersant for the Cu crystallites during the reaction.

Plastics, fibers and rubber are three mainstream synthetic materials that are essential to our daily lives and contribute significantly to the quality of our lives. The production of the monomers of these synthetic polymers usually involves oxidation or ammoximation reactions of olefins and analogues. However, the utilization of C, O and N atoms in current industrial processes is <80%, which represents the most environmentally polluting processes for the production of basic chemicals. Through innovation and integration of catalytic materials, new reaction pathways, and reaction engineering, the Research Institute of Petroleum Processing, Sinopec Co., Ltd. (RIPP) and its collaborators have developed unique H2O2-centered oxidation/ammoximation technologies for olefins and analogues, which has resulted in a & YEN;500 billion emerging industry and driven trillions of & YEN;s' worth of downstream industries. The chemical and engineering bases of the production technologies mainly involve the integration of slurry-bed reactors and microsphere catalysts to enhance H2O2 production, H2O2 propylene/chloropropylene epoxidation for the production of propylene oxide/epichlorohydrin, and integration of H2O2 cyclohexanone ammoximation and membrane separation to innovate the caprolactam production process. This review briefly summarizes the whole process from the acquisition of scientific knowledge to the formation of an industrial production technology by RIPP. Moreover, the scientific frontiers of H2O2 production and related oxidation/ammoximation processes of olefins and analogues are reviewed, and new technological growth points are envisaged, with the aim of maintaining China's standing as a leader in the development of the science and technologies of H2O2 production and utilization.

The exfoliation of bulk C 3 N 4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation-decomposition (NID) strategy that is effective in peeling off BCN into few-layer C 3 N 4 (fl-CN) with tailored thickness down to bi-layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO 3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl-CN, which is conducive to O 2 adsorption and hence relevant chemical processes. In photocatalytic O 2 reduction under visible light irradiation, the H 2 O 2 production rate over the optimal fl-CN-530 catalyst is 952 μmol g −1  h −1 , which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH 4 can be photocatalytically oxidized by on-site formed H 2 O 2 and active oxygen species to generate value-added C1 oxygenates with high selectivity of 99.2 % and record-high production rate of 1893 μmol g −1  h −1 among the metal-free C 3 N 4 -based photocatalysts.

Producing 1,4-butanediol with selective hydrogenation of maleic anhydride has significant financial benefits. This work reported a "green" one-step method for preparing 1,4-butanediol from maleic anhydride in a gas-phase fixed bed continuous flow reactor over an efficient 2Re/CuZnZr catalyst for the first time. In this paper, CuZnZr composite metal oxides were synthesized using the co-precipitation technique, followed by impregnation of Re to produce xRe/CuZnZr catalysts. The study aimed to investigate the effects of including Re on the catalyst's structure and performance. The results obtained from the characterization indicate that the presence of Re in the system restricts the growth of Cu0 grains. In addition, the inclusion of Re facilitated the utilization of ZnO as an effective spacer, reducing the size and quantity of Cu species agglomerates and enhancing active metal dispersion. This phenomenon may be attributed to being the primary factor responsible for the observed enhancement in the activity of the maleic anhydride hydrogenation reaction. Meanwhile, Re facilitated the transformation of gamma-butyrolactone, an intermediate resulting from the hydrogenation of maleic anhydride into 1,4-butanediol. The 2Re/CuZnZr catalyst exhibited favorable catalytic activity under the conditions of 190 degrees C and 6 MPa, resulting in the complete conversion of maleic anhydride and a selectivity of 85 % towards 1,4-butanediol. The catalyst showed consistent catalytic performance throughout the 200 h. The finding about the impact of Re promoter on Cu-based catalysts has the potential to yield a highly efficient catalytic system for alcohol generation.

To photocatalytically reduce O2 to H2O2 over polymeric carbon nitride (PCN) in high efficiency is essential for practical application but remains a considerable challenge. Herein, we synthesized a K, S, and O co-doped PCN (akut-CN) via one-pot polymerization of urea and thiourea in the presence of KCl and NaOH, which afforded an unprecedentedly high H2O2 production rate of 4.46 mM h-1 under visible light irradiation, about 210 times that over the un-doped PCN. The heteroatom doping and the incorporation of the cyano and hydroxyl groups into akut-CN are identified to enhance light absorption, accelerate the separation and transfer of the photogenerated charges, and improve the surface electronegativity and the O2 adsorption capacity and strength, which collaboratively boosted the reaction kinetics. This work highlights the great potential of the elaborately decorated PCN in photocatalytic O2 reduction to H2O2 and paves the way to the decentralized production and application of H2O2.

The Pt-WOx catalyst system has received much attention for its high activity and selectivity in glycerol hydrogenolysis to 1,3-propanediol (1,3-PDO). In this work, the Ga-doped GaWZrOx solid acid supports (GaWZ) with different W contents were prepared, and then Pt/GaWZ catalysts were prepared by the wetness impregnation method. The effects of the W contents on the physicochemical properties and catalytic performance of the Pt/GaWZ catalysts were systematically investigated. CO chemisorption and X-ray photoelectron spectroscopy (XPS) characterizations revealed that the dispersion of Pt on the GaWZ supports first increasesd with the increase in the W content, reached a maximum of 86% on the Pt/GaWZ(10) catalyst with 10% (w) of W, and then decreased at 15% (w) of W. UV-Vis diffuse reflectance (UV-Vis DRS), Fourier transform infrared (FTIR), and XPS characterization showed that the W in the Pt/GaWZ catalysts interacted with the Zr-OH functional groups on the tetragonal phase ZrO2, thus forming mono-dispersed WOx species. When the W content was greater than 7.5% (w), the second layer of the WOx species began to emerge. The mono-dispersed WOx species may be conducive to the high dispersion of Pt. The results of the temperature-programmed desorption of NH3 (NH3-TPD) and pyridine adsorption infrared (Py-IR) characterizations showed that the higher the W content, the higher the amount of the acid on the catalyst, with the simultaneous increase in the amounts of both the Bronsted acids and Lewis acids. In glycerol hydrogenolysis over the Pt/GaWZ catalysts, with the increase in the W content, the glycerol conversion evolved in a volcano-shaped trend, while the selectivity to the target product 1,3-PDO increased monotonically. The highest yield of 1,3-PDO of 47.5% was achieved over the Pt/GaWZ(10) catalyst, and the catalyst also displayed excellent recycling stability. On the basis of the characterization results, we propose that the Pt dispersion and the synergistic interaction between Pt and WOx species determine the activity of the Pt/GaWZ catalysts in glycerol hydrogenolysis, and the Bronsted acid site pertaining to the WOx species is the key to determine the selectivity to 1,3-PDO over the Pt/GaWZ catalysts, as evidenced by the good linear relationship between the 1,3-PDO selectivity and the amount of the Bronsted acid sites.

Polymeric carbon nitride (PCN) is an important metal-free photocatalyst for visible light-driven hydrogen peroxide (H2O2) production from O2 reduction. Herein, we synthesized the DPCN catalysts possessing nitrogen defects by one-step thermal polymerization of urea in N2 stream. As compared to the PCN con-ventionally synthesized in static air, X-ray photoelectrons spectroscopy (XPS) characterization disclosed that there are more pyridinic N defects in the DPCN catalysts, which is attributed to the removal of a pro-portion of NH3 released from urea pyrolysis by flowing N2. UV-vis diffuse reflectance spectroscopy (UV- vis DRS), Mott-Schottky, steady-state and time-resolved photoluminescence (PL), and electrochemical impedance spectroscopy (EIS) characterizations revealed that the introduction of the nitrogen defects narrows down the band gap, improves the density of the photoexcited charge carriers, prolongs the life-time of the charge carriers, and enhances the charge transfer efficiency. In visible light-driven photocat-alytic O2 reduction to H2O2, the optimal DPCN catalyst afforded an activity of 4.35 times that of the PCN catalyst and a H2O2 concentration of 2.83 mmol L-1 after 10 h of visible light irradiation. This one-step thermal polymerization approach is valid when replacing N2 stream with Ar and He streams.(c) 2022 Elsevier Inc. All rights reserved.

Electrochemical production of H2O2 from O-2 via the two-electron reaction pathway (2e-ORR) is a promising alternative to the energy-and organic pollutant-intensive industrial anthraquinone process. However, irrespective of numerous research efforts on catalyst design and remarkable advances made in this area, the catalysts displaying high H2O2 production rate so far unexceptionally required expensive/hazardous catalyst precursors and involved tedious steps and/or harsh treating conditions. Herein, we report a slightly nitrogen-doped carbon 2e-ORR catalyst that was synthesized simply by pyrolyzing a polydopamine (PDA) coating on Vulcan XC72 carbon black (p-PDA/XC). In H2O2 production via ORR in an acidic electrolyte, the catalyst showed 185 mV less overpotential than XC and remarkably high selectivity up to 96%. Highly efficient and durable H2O2 production was demonstrated by the stable accumulation of H2O2 to 1368 mmol g(cat)(-1 )within 8 h, translating to a H2O2 production rate of 171 mmol g(cat)(-1) h(-1). A good linear relationship was identified between the H2O2 partial current and the surface content of the C-O/C-N and C=O species for the XC and p-PDA/XC catalysts, inferring that the C atoms in or adjacent to these species serve as the active sites for 2e-ORR to H2O2. The inexpensive starting materials, facile synthetic strategy, and excellent catalytic performance of the p-PDA/XC catalyst may accelerate the establishment of an affordable, safe, and direct O-2- to-H2O2 electrochemical process.