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Graphitic carbon nitride (gCN) is an important heterogeneous metal-free catalytic material. Thermally induced post-synthetic modifications, such as amorphization and/or reduction, were recently used to enhance the photocatalytic response of these materials for certain classes of organic transformations, with structural defects possibly playing an important role. The knowledge of how these surface modifications modulate the photocatalytic response of gCN is therefore not only interesting from a fundamental point of view, but also necessary for the development and/or tuning of metal-free gCN systems with superior photo-catalytic properties. Herein, employing density functional theory calculations and combining both the periodic and molecular approaches, in conjunction with experimental EPR measurements, we demonstrate that different structural defects on the gCN surface generate distinctive radical defect states localized within the electronic bandgap, with only those correlated with amorphous and reduced gCN structures being photo-active. To this end, we (i) model defective gCN surfaces containing radical defect states; (ii) assess the interactions of these defects with the radical precursors involved in the photo-driven alkylation of electron-rich aromatic compounds (namely perfluoroalkyl iodides); and (iii) describe the photo-chemical processes triggering the initial step of that reaction at the gCN surface. We provide a coherent structure/photo-catalytic property relationship on defective gCN surfaces, elaborating how only specific defect types act as binding sites for the perfluoroalkyl iodide reagent and can favor a photo-induced charge transfer from the gCN surface to the molecule, thus triggering the perfluoroalkylation reaction.

In this work, we explored a post-synthetic modification of the well-known graphitic carbon nitride (g-CN) by means of an "amorphization" treatment and evaluate the resulting change in photocatalytic activity towards the synthesis of valuable perfluoroalkyl derivatives. The as-prepared "super-amorphous" CN (SACN) exhibits a significant increase of the photocatalytic activity (up to a six-fold enhancement with the optimum structure with respect to g-CN), which originates from the lower degree of crystallinity of the CN and its reduced bandgap. The SACN photocatalysts display versatility and good tolerance towards functional group variations of the reagents, emerging as a potential new benchmark CN structure for heterogeneous organic photocatalysis.

Recently, the field of dual photocatalysis has grown rapidly, to become one of the most powerful tools for the functionalization of organic molecules under mild conditions. In particular, the merging of Earth-abundant nickel-based catalytic systems with visible-light-activated photoredox catalysts has allowed the development of a number of unique green synthetic approaches. This goes in the direction of ensuring an effective and sustainable chemical production, while safeguarding human health and environment. Importantly, this relatively new branch of catalysis has inspired an interdisciplinary stream of research that spans from inorganic and organic chemistry to materials science, thus establishing itself as one dominant trend in modern organic synthesis. This Review aims at illustrating the milestones on the timeline evolution of the photocatalytic systems used, with a critical analysis toward novel applications based on the use of photoactive two-dimensional carbon-based nanostructures. Lastly, forward-looking opportunities within this intriguing research field are discussed.

In this work, the development of a novel efficient heterogeneous catalytic system capable of driving Knoevenagel condensation reactions between benzaldehydes and malononitrile was reported. Specifically, we explored a post-synthetic modification of graphitic carbon nitride (g-CN) through a strong oxidation treatment by acid mixture (HNO3/H2SO4). The as-prepared oxidized CN material (CNO) shows a large number of surface acidic moieties, that can be easily deprotonated through an aqueous alkaline wash with different bases (NaOH, K2CO3, t-BuOK), to introduce a high density of reactive basic sites. The best catalyst is obtained with NaOH as the base (CNO-NaOH), and displays high reactivity and good tolerance towards functional group variations of the reagents, thus emerging as a potential new recyclable carbon nitride-based structure for organic base catalysis.

In recent years, the field of dual photocatalysis has become an increasingly popular tool for the functionalization of organic substrates under mild operative conditions. Single-atom heterogeneous catalysts (SACs), where the metal atoms are stabilized by means of properly structured photoactive supports, are currently one of the frontiers of this research field. To this end, Carbon Nitrides (CNs) have emerged as ideal two-dimensional semiconducting supports, capable of stabilizing single metal sites (for instance: nickel, iron, among other) through nitrogen-rich structures. This Concept highlights the recent advances in the synthesis of carbon nitride-based SACs and their applications in light-driven dual-catalytic processes, also providing forward-looking opportunities within this research area.

Carbon nitride (CN) is a heterogeneous photocatalyst that combines good structural properties and a broad scope. The photocatalytic efficiency of CN is associated with the presence of defective and radical species. An accurate description of defective states—both at a local and extended level—is key to develop a thorough mechanistic understanding of the photophysics of CN. In turn, this will maximise the generation and usage of photogenerated charge carriers and minimise wasteful charge recombination. Here the influence of morphology and light-excitation on the number and chemical nature of radical defects is assessed. By exploiting the magnetic dipole-dipole coupling, the spatial distribution of native radicals in CN is derived with high precision. From the analysis an average distance in the range 1.99–2.34 nm is determined, which corresponds to pairs of radicals located approximately four tri-s-triazine units apart.

The integration of graphene oxide (GO) into nanostructured Bi2O3 electrocatalysts for CO2 reduction (CO2RR) brings up remarkable improvements in terms of performance toward formic acid (HCOOH) production. The GO scaffold is able to facilitate electron transfers toward the active Bi2O3 phase, amending for the high metal oxide (MO) intrinsic electric resistance, resulting in activation of the CO2 with smaller overpotential. Herein, the structure of the GO-MO nanocomposite is tailored according to two synthetic protocols, giving rise to two different nanostructures, one featuring reduced GO (rGO) supporting Bi@Bi2O3 core–shell nanoparticles (NP) and the other GO supporting fully oxidized Bi2O3 NP. The two structures differentiate in terms of electrocatalytic behavior, suggesting the importance of constructing a suitable interface between the nanocarbon and the MO, as well as between MO and metal.

Unprotected dipeptides are attractive building blocks for environmentally friendly hydrogel biomaterials by virtue of their low-cost and ease of preparation. This work investigates the self-assembling behaviour of the distinct stereoisomers of Ile-Phe and Phe-Ile in phosphate buffered saline (PBS) to form hydrogels, using transmission electron microscopy (TEM), attenuated total reflectance infrared spectroscopy (ATR-IR), circular dichroism (CD), and oscillatory rheometry. Each peptide purity and identity was also confirmed by 1 H- and 13 C-NMR spectroscopy and HPLC-MS. Finally, single-crystal XRD data allowed the key interactions responsible for the supramolecular packing into amphipathic layers or water-channels to be revealed. The presence of the latter in the crystal structure is a distinctive feature of the only gelator of this work that self-organizes into stable hydrogels, with fast kinetics and the highest elastic modulus amongst its structural isomers and stereoisomers.

HNO3-oxidized carbon nanotubes catalyze oxidative dehydrogenative (ODH) carbon-carbon bond formation between electron-rich (hetero)aryls with O-2 as a terminal oxidant. The recyclable carbocatalytic method provides a convenient and an operationally easy synthetic protocol for accessing various benzofused homodimers, biaryls, triphenylenes, and related benzofused heteroaryls that are highly useful frameworks for material chemistry applications. Carbonyls/quinones are the catalytically active site of the carbocatalyst as indicated by model compounds and titration experiments. Further investigations of the reaction mechanism with a combination of experimental and DFT methods support the competing nature of acid-catalyzed and radical cationic ODHs, and indicate that both mechanisms operate with the current material.

Self-assembling peptides are being applied both in the biomedical area and as building blocks in nanotechnology. Their applications are closely linked to their modes of self-assembly, which determine the functional nanostructures that they form. This work brings together two structural elements that direct nanoscale self-association in divergent directions: proline as a β-breaker and the β-structure-associated diphenylalanine motif, into a single tripeptide sequence. Amino acid chirality was found to resolve the tension inherent to these conflicting self-assembly instructions. Stereoconfiguration determined the ability of each of the eight possible Pro-Phe-Phe stereoisomers to self-associate into diverse nanostructures, including nanoparticles, nanotapes, or fibrils, which yielded hydrogels with gel-to-sol transition at a physiologically relevant temperature. Three single-crystal structures and all-atom molecular dynamics simulations elucidated the ability of each peptide to establish key interactions to form long-range assemblies (i,e., stacks leading to gelling fibrils), medium-range assemblies (i.e., stacks yielding nanotapes), or short-range assemblies (i.e., dimers or trimers that further associated into nanoparticles). Importantly, diphenylalanine is known to serve as a binding site for pathological amyloids, potentially allowing these heterochiral systems to influence the fibrillization of other biologically relevant peptides. To probe this hypothesis, all eight Pro-Phe-Phe stereoisomers were tested in vitro on the Alzheimer's disease-associated Aβ(1-42) peptide. Indeed, one nonfibril-forming stereoisomer effectively inhibited Aβ fibrillization through multivalent binding between diphenylalanine motifs. This work thus defined heterochirality as a useful feature to strategically develop future therapeutics to interfere with pathological processes, with the additional value of resistance to protease-mediated degradation and biocompatibility.

Oxidized active carbon (oAC) catalyses the formation of polysubstituted quinolines from o-vinyl anilines and aldehydes. The reaction proceeds in a cascade manner through condensation, electrocyclization and dehydrogenation, and gives access to a wide range of quinolines with alkyl and/or aryl substituents as demonstrated with 40 examples. The metal-free catalytic procedure allows a heterogeneous protocol for the synthesis of various polysubstituted quinolines. The mechanistic studies imply that both the acid and quinoidic groups in oAC are integral for the catalytic manifold. (Figure presented.).

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In this Chem issue, Han et al. devised a system relying on tandem heterogeneous and homogeneous catalysis by ruthenium species for the CO2 hydrogenation to hydrocarbons with remarkable efficiency. In particular, 5-atom (or longer) chain hydrocarbons were obtained with remarkably high selectivity (71.1%).

Electrocatalytic Nitrogen Reduction Reaction (NRR) to ammonia is one of the most recent trends of research in heterogeneous catalysis for sustainability. The stark challenges posed by the NRR arise from many factors, beyond the strongly unfavored thermodynamics. The design of efficient heterogeneous electrocatalysts must rely on a suitable interplay of different components, so that the majority of research is focusing on development of nanohybrids or nanocomposites that synergistically harness the NRR sequence. Nanostructured carbon is one of the most versatile and powerful conductive supports that can be combined with metal species in an opportune manner, so as to guide the correct proceeding of the reaction and boost the catalytic activity.

Visible light-driven production of fuels and value-added chemicals is currently one of the most intensely investigated research topics across various scientific disciplines, due to its potential to ease the World’s dependence on fossil fuels. In this perspective, we recapitulate some of the main features of dye-sensitized photocatalytic systems aimed at solar H2 production, focusing in particular on TiO2-based three-component assemblies with organic sensitizers. Relevant aspects include the structural and electronic properties of the sensitizers, the nature of the semiconductor and the hydrogen evolution catalysts, the role of the sacrificial donor and the effect of the reaction parameters on H2 production rate and stability. Besides presenting the most significant recent developments of the field, we also analyse some of its common practices in terms of experimental design, laboratory procedures and data presentation, trying to highlight their weaknesses and suggesting possible improvements. We then conclude with a short paragraph discussing the possible future development of this exciting research area.

The electrocatalytic CO2 reduction reaction (CO2RR) is an interfacial process, involving a minimum of three phases at the contact point of gaseous CO2 with the electrodic surface and the liquid electrolyte. As a consequence, surface chemistry at composite interfaces plays a central role for CO2RR selectivity and catalysis. Each interface defines a functional boundary, where active sites are exposed to a unique environment, with respect to distal sites in the bulk of organic and inorganic domains. While the individual role of each component-type is hardly predictable "a-solo", the interface ensemble works via a strategic interplay of individual effects, including: (i) enhanced electrical conductivity, (ii) high surface area and exposure of the interfacial catalytic sites, (iii) favorable diffusion and feeding of reactants, (iv) complementary interactions for the "on/off" stabilization of cascade intermediates, (v) a secondary sphere assistance to lower the activation energy of bottleneck steps, (vi) a reinforced robustness and long-term operation stability. Selected CO2RR case studies are compared and contrasted to highlight how the organic domains of carbon nanostructures merge with metal and metal-oxide active sites to separate tasks but also to turn them into a cooperative asset of mutual interactions, thus going beyond the classic "Divide et Impera" rule.

Ceria (CeO2) nanostructures are well-known in catalysis for energy and environmental preservation and remediation. Recently, they have also been gaining momentum for biological applications in virtue of their unique redox properties that make them antioxidant or pro-oxidant, depending on the experimental conditions and ceria nanomorphology. In particular, interest has grown in the use of biotemplates to exert control over ceria morphology and reactivity. However, only a handful of reports exist on the use of specific biomolecules to template ceria nucleation and growth into defined nanostructures. This review focusses on the latest advancements in the area of biomolecular templates for ceria nanostructures and existing opportunities for their (bio)applications.

Practical-scale on-site production of hydrogen peroxide (H2O2) via two-electron (2e(-)) oxygen reduction reaction (ORR) relies on efficient, robust, and selective electrocatalysts. Among them, carbon-based materials are cheap, abundant, durable, and their surface properties can be tuned to favor the 2e(-) ORR pathways, resulting in higher efficiency and facilitating possible scale-up towards commercially appealing levels. Here, we demonstrate that the selective installment of carboxyl groups on the surface of N-doped graphene yielding a material named graphene acid (N-GA) promotes the catalytic 2e(-) ORR, achieving a H2O2 faradaic efficiency (FE) as high as 70 % in acidic media (pH=0.96) and a H2O2 productivity in long term bulk electrolysis that could reach 107.8 mmol g(catalyst)(-1) h(-1) under optimized conditions. Extended XPS analysis and density functional theory (DFT) calculations revealed that surface carboxylic acid functional groups play a significant role in achieving the high activity of N-GA for 2e(-) ORR.

In-depth analysis of structure/activity relationship aids rational design of modified carbon nitride for organophotocatalysis., The favorable exploitation of carbon nitride (CN) materials in photocatalysis for organic synthesis requires the appropriate fine-tuning of the CN structure. Here, we present a deep investigation of the structure/activity relationship of CN in the photocatalytic perfluoroalkylation of organic compounds. Four types of CN bearing subtle structural differences were studied via conventional characterization techniques and innovative nuclear magnetic resonance (NMR) experiments, correlating the different structures with the fundamental mechanistic nexus and especially highlighting the importance of the halogen bond strength between the reagent and the catalyst surface. The optimum catalyst exhibited an excellent performance, with a very wide reaction scope, and could prominently trigger the model reaction using natural sunlight. The work lays a platform for establishing a new approach in the development of heterogeneous photocatalysts for organic synthesis related to medical, agricultural, and material chemistry.

The uncapped tripeptide DPhe-Phe-Leu acts as self-assembly template to yield supramolecular hydrogel biomaterials. As an example, self-assembling DPhe-Phe-Leu-Asp-Val contains the LDV bioadhesive motif for β1 integrin activation. Hydrogels made of the two peptides successfully mimic fibronectin of the extracellular matrix and lead to high cell viability, adhesion, and spreading.

The importance of sensing hydrogen peroxide (H2O2) is due to its ubiquity, being extensively used in industry and also being a biologically relevant side-product of several enzymatic processes. Electrochemical sensing is one of the most robust and simple methods for sensing H2O2 and the discovery of new electroactive materials, particularly at the nanoscale, represents a very hot topic of research. Here, we prove that upon appropriate integration of oxidized single-walled carbon nanohorns (ox-SWCNHs) into a per se moderate H2O2 sensor such as cerium dioxide (CeO2), the sensitivity toward H2O2 is enhanced by almost two orders of magnitude (from 0.4 to 160 μA cm−2 mM−1), on par with that of state-of-the-art metal or metal oxide-based sensors. The modified electrode is also very stable (82% response after 2 weeks of continuous use) and the results highly reproducible. The developed nanohybrid ox-SWCNHs@CeO2, characterized fully and whose average size is about 70 nm as measured by both TEM and AFM, was also tested in real case studies such as washing liquids and milk and was confirmed to be a robust and highly selective material, being not affected neither by the presence of complex matrices, nor by interferents in several organic substrates. The high recovery confirmed the excellent specificity and flexibility of this new electrocatalytic material. Fil: Bracamonte, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. University of Trieste; Italia Fil: Melchionna, Michele. University of Trieste; Italia Fil: Giuliani, Angela. University of Trieste; Italia Fil: Nasi, Lucía. CNR-IMEM Institute; Italia Fil: Tavagnacco, Claudio. University of Trieste; Italia Fil: Prato, Maurizio. University of Trieste; Italia. Carbon Nanobiotechnology Laboratory; España. BasqueFdnSci; España Fil: Fornasiero, Paolo. University of Trieste; Italia

Electrocatalysis, particularly related to fuel cell applications or other processes related to sustainability, has been steadily advanced by the design of new hierarchical materials involving two or more phases. One particularly appealing type of structure features metal species confined within carbon layers. These materials combine the benefits of the two components, which often work in synergy. However, given the intrinsic catalytic activity of carbon and the fact that the metal may be chemically inaccessible, in many cases, which of the two phases is the truly active site is not fully clear. Particularly for pure core–shell systems, where the metal is completely covered by carbon, the identification of the specific task of each component is not trivial. Many reported works on this type of bi-component catalyst are speculative in this regard. It is important for catalyst development that future studies on these systems will include a thorough cross-check of the reactivity aspects by means of combination of suitable techniques or experiments to unravel probable mechanisms and that assumptions are avoided.

Protein and peptide phosphorylation regulate numerous pathological processes, however, their characterization is challenging due to their low abundance and transient nature. Therefore, nanomaterials are being developed to address this demanding task. In particular, carbon nanostructures are attracting interest as scaffolds for functional nanocomposites, yet only isolated studies exist on the topic, and little is known on the effect of nanocarbon morphology on templating nanocomposites. In this work, we compared oxidized carbon nanotubes, graphene oxide, oxidized carbon nanohorns and oxidized graphitized carbon black, as scaffolds for magnetized nanocomposites. The nanomaterials were extensively characterized with experimental and in silico techniques. Next, they were applied to phosphopeptide enrichment from cancer cell lysates for NanoHPLC-MS/MS, with selectivity as high as nearly 90% and several-thousand identification hits. Overall, new insights emerged for the understanding and the design of nanocomposites for phosphoproteomics.[Figure not available: see fulltext.]

The combination of multiwalled carbon nanotubes (MWCNTs) with undoped CeO2 nanoparticles (NPs) is effective for the direct electrocatalytic reduction of CO2 to formic acid (FA) at acidic pH (0.1 M HNO3), at overpotential as low as eta = -0.02 V (vs RHE) with Faradic efficiency (FE) up to 65%. Ex situ and operando evidence identifies nonstoichiometric Ce4+/3+O2-x reduced sites as essential for the selective CO2 reduction reaction (CO2RR). The MWCNT-mediated electrochemical reduction of the CeO2 NPs offers a definite advantage with respect to the generally adopted thermochemical cycles (800-1500 degrees C) or deep hydrogenation pretreatments, thus presenting an interesting perspective for the engineering of CeO2 electrocatalysts.

Introduction: “Here comes the sun, and I say it’s alright”. The line from the famous and comforting Beatles’ song sounds like a perfect slogan for today’s crusade toward a more sustainable world. A never-tiring memento that, as long as the Sun shines in the sky, there will always be hope to heal a world suffering from an impressive increase in energetic demand. Sunlight brings a gigantic energy pack, and modern scientists are investing a huge amount of time, resources, and intellectual exercise into best exploiting it. Therefore, the fast-growing number of discoveries on photocatalysis comes as no surprise, and quite obviously they are accompanied by a ballistic number of publications (Figure 1). However, is this latter number truly justified or is the chain of events pining for sustainability and clean energy generating an overpopulation of contributions to the topic? Assuming that all such publications always reach a minimum standard of quality and novelty, the question for now must remain unanswered, because research is an unpredictable animal that can feed from any little fruit. However, a different but relevant question could be possibly answered: is it possible to establish a common protocol, set of rules, that makes all these publications useful for moving forward in a harmonized fashion the knowledge on photocatalysis?

The Oxygen Reduction Reaction (ORR) catalyzed by N-carbon electrocatalyst was investigated, focusing on the fundamental features for the selective H2O2 formation. The electrochemical characterization was primarily performed by the use of the Rotating Ring Disk Electrode (RRDE) tool in both hydrodynamic Linear Sweep Voltammetry (LSV) mode and by Chronoamperometry (CA) measurement. We rationalized the structure/activity relationship, reaching a new state-of-the-art in terms of current density for the H2O2 generation. The study also explored the performance in relation with the electrode deposit procedure that is of fundamental importance to achieve a suitable macroscopic electrode preparation. Furthermore, the electrode implementation in a polymer membrane static flow electrolyzer setup, was evaluated to understand how the material catalytic features such as current ranges and selectivity scale up from a classical three electrode system to a more realistic application-focused environment.

The exceptional and unique properties of cerium dioxide have encouraged scientists to exploit this material beyond its traditional role as a promoter in automotive engines. Electrochemical processes relevant to fuel cells, electrolyzers, and sensors can be facilitated or even directly catalyzed by the CeO2, whose redox properties are ideal for electrochemistry. However, given the insulating nature of pure ceria, the inclusion of conductive materials at the boundary with the metal oxide is necessary to boost the catalytic activity. Carbon in its various forms and morphologies is a dominant component in ceria-based electrocatalysts, significantly facilitating electron transfers and providing high surface area and improved stability. Moreover, given the improved electronic conductivity of reduced CeO2 in the wake of the decreased grain boundary impedance, the combination with a conductive component, such as carbon, can facilitate a reduction of the ceria.

We report the first histidine-containing self-assembling tripeptide devoid of capping groups that forms a thermoreversible hydrogel under physiological conditions and catalyses hydrolysis of an ester, providing a minimalist building block for functional soft materials.

The influence of phosphorus and water on methane catalytic combustion was studied over Pd@CeO2 model catalysts supported on graphite, designed to be suitable for X-ray Photoelectron Spectroscopy/Synchrotron Radiation Photoelectron Spectroscopy (XPS/SRPES) analysis. In the absence of P, the catalyst was active for the methane oxidation reaction, although introduction of 15% H2O to the reaction mixture did cause reversible deactivation. In the presence of P, both thermal and chemical aging treatments resulted in partial loss of activity due to morphological transformation of the catalyst, as revealed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) analysis. At 600 degrees C the combined presence of PO43- and water vapor caused a rapid, irreversible deactivation of the catalyst. XPS/SRPES analysis, combined with operando X-ray Absorption Near Edge Structure (XANES) and AFM measurements, indicated that water induces severe aggregation of CeO2 nanoparticles, exposure of CePO4 on the outer layer of the aggregates and incorporation of the catalytic-active Pd nanoparticles into the bulk. This demonstrates a temperature-activated process for P-poisoning of oxidation catalysts in which water vapor plays a crucial role. (C) 2015 Elsevier B.V. All rights reserved.

Self-assembled peptide hydrogels have brought innovation to the medicinal field, not only as responsive biomaterials but also as nanostructured therapeutic agents or as smart drug delivery systems. D-amino acids are typically introduced to increase the peptide enzymatic stability. However, there are several reports of unexpected effects on peptide conformation, self-assembly behavior, cytotoxicity and even therapeutic activity. This mini-review discusses all the surprising twists of heterochiral self-assembled peptide hydrogels, and delineates emerging key findings to exploit all the benefits of D-amino acids in this novel medicinal area.

Molecular recognition of C60 fullerene by two cavitands, bearing four and three quinoxaline walls, is reported here. Fluorescence titrations show the recognition ability of the receptors with high binding constant values. The formation of a stable 1:1 supramolecular complex was also confirmed by DOSY, EI-MS and X-ray analysis. The crystal structure analysis of tetraquinoxaline cavitand and C60 shows a crystal packing, where C60 molecules are intercalated between bilayers of cavitand molecules, on the ideal fourfold symmetry axis of the receptor, and are arranged in a zigzag motif.

Electrocatalytic oxygen reduction (ORR) is an emerging synthetic strategy to prepare H

Electrocatalytic oxygen reduction (ORR) is an emerging synthetic strategy to prepare H2 O2 in a sustainable fashion. N-doped graphitic carbon with embedded cobalt nanoparticles was selected as an advanced material able to selectively trigger the ORR to form H2 O2 with a faradaic efficiency of almost 100 % at very positive applied potentials. The production of H2 O2 proceeded with high rates as calculated by bulk electrolysis (49 mmol g-1 h-1 ) and excellent current densities (≈-0.8 mA cm-2 at 0.5 V vs. reversible hydrogen electrode). The totally selective behavior depended on the combination of concomitant material features, such as the textural properties, the nature of the metal, the distribution of N moieties, the acidic environment, and the applied potential.

In this issue of Chem, Li and co-workers accessed the formation of high-density single Pt atoms thanks to the use of a well-devised support and ion exchange. The high Pt density in isolated form causes a high selectivity and rate toward the formation of hydrogen peroxide from the electrochemical reduction of oxygen.

One of the recent trends in electrocatalytic reactions involves the oxygen reduction reaction (ORR), where a new paradigm has been shaped to exploit this reaction for the synthesis of hydrogen peroxide (H2 O2 ). H2 O2 is a very versatile chemical of high commercial value, prepared currently through poorly sustainable processes. The emergence of metal-free carbon catalysts for the selective synthesis of H2 O2 is expected to revolutionize ORR research, beckoning at the development of new industrial schemes. The complexities of the mechanism and the factors dominating the selectivity of the process have been unveiled through a combination of theoretical and experimental studies.