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CDs were used to modify an organic semiconductor of p(DB) and the optimal sample exhibits efficient H2 evolution under visible light in an o-xylene-in-water emulsion by photo-splitting of water. The CDs play both the roles of cocatalyst and reactor.

Cu5FeS4 quantum dots as a single-component photo-assisted electrocatalyst for efficient hydrogen evolution reaction superior to Pt/C.

Porous flexible iridium nanosheets (Ir-PFNSs) with compressive strain were obtained by annealing 3R phase iridium oxide (3R-IrO2) in a hydrogen atmosphere, which can exhibit excellent acid HER activity by a new three-hydrogen-involved mechanism.

Carbon dots (C-Dots), with unique properties from tunable photoluminescence to biocompatibility, show wide applications in biotechnology, optoelectronic device and catalysis. Chiral C-Dots are expected to have strongly chirality-dependent biological and catalytic properties. For chiral C-Dots, a clear structure and quantitative structure-property relationship need to be clarified. Here, chiral C-Dots were fabricated by electrooxidation polymerization from serine enantiomers. The oxidized serine has a reversed chiral configuration to serine, which leads to the chiral C-Dots possessing inverse handedness compared with their raw materials. Electron circular dichroism spectrum, together with other diverse characterization techniques and theoretical calculations, confirmed that these chiral C-Dots (2-7 nm) have a well-defined primary structure of polycyclic dipeptide and possess a spatial structure with a

Metastable metal oxides with ribbon morphologies have promising applications for energy conversion catalysis, however they are largely restricted by their limited synthesis methods. In this study, a monoclinic phase iridium oxide nanoribbon with a space group of C2/m is successfully obtained, which is distinct from rutile iridium oxide with a stable tetragonal phase (P42/mnm). A molten-alkali mechanochemical method provides a unique strategy for achieving this layered nanoribbon structure via a conversion from a monoclinic phase K0.25IrO2 (I2/m (12)) precursor. The formation mechanism of IrO2 nanoribbon is clearly revealed, with its further conversion to IrO2 nanosheet with a trigonal phase. When applied as an electrocatalyst for the oxygen evolution reaction in acidic condition, the intrinsic catalytic activity of IrO2 nanoribbon is higher than that of tetragonal phase IrO2 due to the low d band centre of Ir in this special monoclinic phase structure, as confirmed by density functional theory calculations.

Highly stable CD-modified Co3O4/In2O3 photocatalysts for efficient solar-driven CO2 reduction. With regard to economic cost, the CO generation rate of the CD catalyst is dramatically improved, up to 761 times, compared with that of the Ru catalyst.

O2 serves as both a reactant and an electron sink to enhance the H2O2 production in the photocatalytic process with this the novel photocatalyst.

Rh/RhOx nanosheet electrocatalysts designed with Rh–O–Rh interfaces regulate the distance between the active site and the intermediate and effectively generate hydrogen in electrolytes of different pH values containing hydrazine.

The assembly of the heterogeneous microreactor is a promising approach for CO2 photoreduction attributed to its abundant microchannel, intimate contact, high exposed surface area, and favorable heat-mass transfer.

Metal-organic frameworks (MOFs) are regarded as one promising class of precatalysts for electrocatalytic oxygen evolution reaction (OER), yet most of them suffer from poor conductivity and lack of coordinatively unsaturated metal sites, which hinders the fast electrochemical reconstruction and thus a poor OER activity. To address this issue, a unique heterocomposite has been constructed by in situ inserting carbon dots (CDs) into cobalt-based zeolitic imidazolate framework (Co-ZIF) nanosheet arrays (Co-ZIF/CDs/CC) in the presence of carbon cloth (CC) via one-pot coprecipitation for alkaline OER. Benefiting from the synergism between CDs and Co-ZIF subunits such as superior conductivity, strong charge interaction as well as abundant metal sites exposure, the Co-ZIF/CDs/CC exhibits an enhanced promotion effect for OER and contributes to the deep phase transformation from CDs-coupled Co-ZIF to CDs-coupled active CoOOH. As expected, the achieved Co-ZIF/CDs/CC only requires an overpotential of 226 mV to deliver 10 mA cm

ConspectusAs a new kind of carbon based functional material, carbon dots (CDs) have sparked much interest in recent years. The tunable structure, composition, and morphology of CDs unlocks opportunities to enable diversity in their photoelectrochemical properties, and thus they show great potential in various applications such as biology, catalysis, sensors, and energy storage. Nevertheless, the related understanding of CDs is insufficient at present due to their inherent complexity of microstructure, which involves the intersection of high polymer, bulk carbon, and quantum dot (QD). A good understanding of the underlying mechanism behind the properties of CDs is still a formidable challenge, requiring the integration of robust knowledge from organic chemistry, materials science, and solid state physics. Within this context, discovering more appealing properties, elucidating fundamental factors that affect the properties and proposing effective engineering strategies that can realize specific functions for CDs are now highly pursued by researchers.At the beginning of this Account, the main features of CDs are introduced, where not only the basic structural, compositional and morphological characteristics but also the rich photoelectrochemical properties are elucidated, among which the band gap, chirality, photoinduced potential, and electron sink effect are particularly emphasized. Furthermore, new analysis techniques including transient photoinduced current (TPC), transient photoinduced voltage (TPV), and machine learning (ML) to reveal the unique properties of CDs are described. Then, several appealing strategies that aim to rationally tailor CDs for oriented applications are highlighted. These regulation strategies are morphology modulation (e.g., developing CDs with new geometrical configuration, controlling the particle size), phase engineering (e.g., altering the phase crystallinity, introducing the foreign atoms), surface functionalization (e.g., grafting various types of functional groups), and interfacial tuning (e.g., building CD-based nanohybrids with well-defined interfaces). Although the fundamental investigation of CDs is relatively undeveloped because of their complexity, this does not hinder their wide application. At the same time, exploring the extensive applications of CDs will promote their in-depth understanding. Finally, the chances for building a CD-centered blueprint for sustainable society are explored and challenges for future research in the field of CDs are proposed as follows: (i) the controllable synthesis of CDs with uniform size; (ii) search for novel CDs with unique structure, morphology, or composition; (iii) quantitative understanding of the property of CDs; (iv) performance enhancement by external forces such as magnetism or heat injection; (v) construction of the dual carbon concept; (vi) further research on different photocatalytic applications. On the whole, this Account may provide meaningful references for the understanding of the microstructure-property correlation as well as the regulation of CDs, thereby promoting their transition from fundamental research to practical application.

Designing well-ordered nanocrystal arrays with subnanometre distances can provide promising materials for future nanoscale applications. However, the fabrication of aligned arrays with controllable accuracy in the subnanometre range with conventional lithography, template or self-assembly strategies faces many challenges. Here, we report a two-dimensional layered metastable oxide, trigonal phase rhodium oxide (space group, P-3m1 (164)), which provides a platform from which to construct well-ordered face-centred cubic rhodium nanocrystal arrays in a hexagonal pattern with an intersurface distance of only 0.5 nm. The coupling of the well-ordered rhodium array and metastable substrate in this catalyst triggers and improves hydrogen spillover, enhancing the acidic hydrogen evolution for H2 production, which is essential for various clean energy-related devices. The catalyst achieves a low overpotential of only 9.8 mV at a current density of −10 mA cm−2, a low Tafel slope of 24.0 mV dec−1, and high stability under a high potential (vs. RHE) of −0.4 V (current density of ~750 mA cm−2). This work highlights the important role of metastable materials in the design of advanced materials to achieve high-performance catalysis.

As a unique carbon-based nano material, carbon dots (CDs) have attracted great attention because of their special structures and properties, and have been widely used in various fields, such as bio-imaging technology, catalyst design, pollutant degradation, chemical analysis, clean energy development and so on. CDs are used as catalysts or cocatalysts for multiple energy conversion reactions due to their advantages of valid visible light utilization, fast transmission of charge carriers, excellent catalytic activity, and good electrical conductivity. This review first summarizes the basic structure and properties of CDs. The advance and critical functions of energetic CDs in carbon dioxide photo/electroreduction reactions are discussed in detail. Due to the excellent optical absorption, electron transfer properties and good conductivity of CDs, they can enhance catalytic activity and stability effectively. In the end, the existing problems and future development opportunities of CDs-based catalysts in CO

Overall water photo-splitting is a prospective ideal pathway to produce ultra-clean H2 energy by semiconductors. However, the band structure of many semiconductors cannot satisfy the requirement of H2 and O2 production at the same time. Herein, we illustrate that carbon dots (CDs)/Bi2WO6 photocatalyst with compensatory photo-electronic effect has enhanced activity for overall water photo-splitting without any sacrificial agent. In this complex photocatalytic system, the photo-potential provided by CDs makes the CDs/Bi2WO6 (C-BWO) composite could satisfy the band structure conditions for overall water photo-splitting. The C-BWO composite (3 wt% CDs content) exhibits optimized hydrogen evolution (oxygen evolution) of 0.28 μmol/h (0.12 μmol/h) with an approximate 2:1 (H2:O2) stoichiometry at normal pressure. We further employed the in-situ transient photovoltage (TPV) technique to study the photoelectron extraction and the interface charge transfer kinetics of this composite catalyst.

Carbon dots (CDs) with enzyme-like activities play crucial roles in nanobiotechnology. However, it is difficult to establish a relationship between their structure and biocatalytic properties. In this work, a series of nitrogen-doped carbon dots (TA-NCDs) were synthesized by a hydrothermal method. Their oxidase-like activity could be triggered by visible light irradiation (420 nm≤λ ≤ 700 nm). As a nanozyme, TA-NCDs show the value of maximum reaction rates (Vmax) is 121.95 × 10−8 M/s and the Michaelis–Menten constants (Km) is 0.61 mM. In situ transient photovoltage (TPV) tests prove that the pyrrolic nitrogen in TA-NCDs is the catalytic active sites and substrate binding sites. Under visible light irradiation, TA-NCDs, with oxidase-like activity, increased the cellular ROS level significantly, leading to their visible light induced bioactivity to kill nearly 60% of HeLa cells.

A photocatalyst system is generally comprises a catalyst and cocatalyst to achieve light absorption, electron-hole separation, and surface reaction. It is a challenge to develop a single photocatalyst having all functions so as to lower the efficiency loss. Herein, the active GaN4 site is integrated into a polymeric carbon nitride (CN) photocatalyst (GCN), which displays an excellent H2 production rate of 9904 μmol h-1 g-1 . It is 162 and 3.3 times higher than that of CN with the absence (61 μmol h-1 g-1 ) and presence (2981 μmol h-1 g-1 ), respectively, of 1.0 wt % Pt. Under light irradiation the electron is injected and stored at the GaN4 site, where the LUMO locates. The HOMO distributes on the aromatic ring resulting in spatial charge separation. Transient photovoltage discloses the electron-storage capability of GCN. The negative GaN4 promotes proton adsorption in the excited state. The positive adsorption energy drives H2 desorption from GaN4 after passing the electron to the proton. This work opens up opportunities for exploring a novel catalyst for H2 production.

Solar-driven water splitting for hydrogen peroxide (H2O2) production is a sustainable and ultra-clean method. It is difficult for a single-component photocatalyst to meet all the requirements for efficient and stable photoproduction of H2O2. Meanwhile, for multiple-component catalysts, a huge and urgent challenge is to adjust the photo-charge between the multiple components and interfaces of catalysts. Herein, we report a metal-free photocatalyst CN1.8/ICT/CDs composed of CN1.8, organic small molecules (ICT) and N, S-doped carbon dots (CDs) to produce H2O2 efficiently and stably through a dual-channel process. In this catalyst system, CDs are first reported as the active site of water oxidation reaction (WOR) and ICT as the active site of oxygen reduction reaction (ORR), with greatly improved efficiency of the use of photo-charge, and the poisoning of CN1.8/ICT/CDs by H2O2 was prevented. In situ transient photovoltage measurements (TPV) further revealed the photo-charge regulation function of CDs in this multiple-component metal-free photocatalyst. As a result, the CN1.8/ICT/CDs catalyst exhibits a prominent H2O2 production rate of 2202.81 μmol h−1 g−1 (λ ≥ 420 nm), which represents the most efficient H2O2 production rate from a metal-free photocatalyst in air atmosphere without sacrificial agents. This work also provides a valid TPV-based method for a deep understanding of complex photocatalytic systems.

The manufacture of blue light-emitting diodes (LEDs) has always been a tough problem to solve in the display and illumination fields. Inorganic/organic semiconductors and carbon dots (CDs) with a wide band gap still face obstacles such as a low external quantum efficiency (EQE) and poor stability. Herein, we synthesized highly stable and blue emission CDs with a chemically inert surface, and the photoluminescence (PL) peak (in ultra-pure water) of which is located at 446 nm with an absolute PL quantum yield (PLQY) of 26.4%. The LEDs based blue emission CDs exhibit an electroluminescence (EL) peak located at 456 nm and a high brightness of 223 cd m−2 with an EQE of 0.856%. The Commission Internationale del'Eclairage (CIE) coordinates are located at (0.21, 0.23) and the device lifetime with 65% brightness (T65) reaches over 217 h because of the chemically inert surface of the CDs. The results mean the devices are the most stable CDs-LEDs reported to date. This work represents a novel route for the preparation of low cost, highly stable and very bright CDs-LEDs with a short wavelength emission.

Hydrogen peroxide (H2O2) is a multi-functional chemical for a range of industries, but the present H2O2 production requires complex processes, and leads to environmental pollution, etc. Solar water-splitting is one of the potential avenues to combine H2O and O2 into H2O2 through a cheap and clean way. Most of the photocatalysts involve multiple components and interfaces to improve the catalytic activity and energy conversion efficiency. However, it is difficult to regulate the photo-charge kinetics between the multi-interface catalyst, which hinders the practical application of photocatalysts. Here, we report a SnS2/In2S3 type II heterostructure modified by carbon dots (SnS2/In2S3/CDs) to highly improve the stability of sulfides and realize generation of H2O2 by the oxygen reduction reaction (ORR). Notably, in situ transient photovoltage measurements (TPV) were carried out to analyze the charge transfer process among SnS2, In2S3 and CDs. The optimal SnS2/In2S3/CD composite (n(Sn):n(In) = 50%) displays a prominent H2O2 production rate of 1111.89 μmol h−1 g−1 without any sacrificial agent under the conditions of normal pressure and neutral solution (pH = 7). The quantum efficiency (QE) of H2O2 production was calculated to be 3.9% under light (λ = 535 nm), and the solar energy conversion efficiency (SCC) was up to 1.02%, which is the highest known production of H2O2 from sulfides as photocatalysts. Our work provides a new way to regulate the photo-charge kinetics of the multi-interface catalyst using CDs to achieve the extremely efficient production of H2O2 by photocatalytic water-splitting.

A double-shell triptycene covalent polymer@CdS hollow sphere (TCP@CdS HS) composite has been successfully synthesized by in situ growing a TCP on the surface of CdS@SiO2 spheres and then removal of the SiO2 template via alkali etching. Characterization indicates that an amorphous TCP layer is coated on the thin CdS shell via an electrostatic self-assembly process, and the TCP layer thickness can be tuned by adjusting TCP loading. The photocatalytic hydrogen generation rate of the optimal TCP@CdS HS composite is up to 9480 μmol h−1 g−1 under visible-light irradiation, which is 57, 37 and 18 times higher than those of pristine CdS HS, SiO2@CdS HS and SiO2@CdS@SiO2, respectively. Besides, the TCP@CdS HS composite possesses excellent stability, which is superior to that of SiO2@CdS HS and SiO2@CdS@SiO2. An in-depth study of the electron transfer process and the photocatalytic mechanism was performed by in situ transient photovoltage experiments, which indicate that the TCP can facilitate the diffusion of hydrogen and stabilize the photoinduced electrons. This work provides an effective strategy to design novel hollow sphere heterostructures for solar energy conversion.

The interfacial dynamic interactions between molecules and cell membranes are critical in many basic biological processes. An effective method for sensitive, real-time, and noninvasive monitoring o...

Although lead halide perovskites are demonstrated to be promising photocatalysts for hydrogen evolution from hydrogen halide splitting, it still remains challenging to fabricate efficient and stabl...

The electrochemical oxygen reduction reaction ORR offers a most promising and efficient route to produce hydrogen peroxide H2O2 , yet the lack of cost effective and high performance electrocatalysts have restricted its practical application. Herein, an entropy enhancement strategy has been employed to enable the low cost perovskite oxide to effectively catalyze the electrosynthesis of H2O2. The optimized Pb NiWMnNbZrTi 1 6O3 ceramic is available on a kilogram scale and displays commendable ORR activity in alkaline media with high selectivity over 91 amp; 8201; across the wide potential range for H2O2 including an outstanding degradation property for organic dyes through the Fenton process. The exceptional performance of this perovskite oxide is attributed to the entropy stabilization induced polymorphic transformation assuring the robust structural stability, decreased charge mobility as well as synergistic catalytic effects which we confirm using advanced in situ Raman, transient photovoltage, Rietveld refinement as well as finite elemental analysis

The chemical origins of life have been widely accepted at the present stage. However, the idea that amino acids further react to produce peptides and proteins remains an unsatisfactory explanation, because producing polypeptides via spontaneous reaction of amino acids in solution is extremely difficult. It is also necessary to further answer whether amino acids can form longer peptide chains as well as specific chiral structures and so on under this same reaction mechanism. Carbon dots (CDs) have been intensively researched over the past years due to their unique chemical and physical properties. Here, we demonstrate the photocatalytic polymerization of amino acids into polypeptides and proteins using CDs as a photocatalyst, in which the synthetic conditions required are only room temperature (or as low as -20 °C) and aqueous conditions along with light irradiation, which are very mild and easy to satisfy. We even obtain a protein with tertiary structures, namely an artificial insulin with the biological function to reduce the blood sugar of the laboratory mice. The innovation of using CDs to initiate amino acids to condense into polypeptides is based on strong adsorption (e.g., hydrogen bonding), the acidity of the -OH surface functional groups, and the photogenerated protons/holes, which are the fundamental factors for polypeptide or even ternary structure protein formation by means of capturing and condensing the amino acids as well as forming the S-S bonds.

Infection of pathogenic bacteria and the abuse of antibiotics are the main factors in worldwide health issues. A number of nanomaterials have been fabricated to directly battle drug-resistant bacteria. However, few studies have referred to the relation between common daily carbon nanoparticles (e.g., automobile exhaust and cigarette smoke) and antimicrobial activities. Herein, carbon dots (CDs) extracted from cigarette smoke are introduced, showing low in vivo and in vitro toxicity. These CDs show broad-spectrum antimicrobial activities that originate from the destruction of the double helix structure of DNA. CDs can degrade to smaller particles and organic fragments with the existence of horseradish peroxidase (HRP) and H2O2 in 7 days, during which CDs can function as an effective antibiotic within the early days and then gradually degrade and lose the antimicrobial effects until finally being eliminated through metabolism. Our findings relate common daily carbon nanoparticles from cigarette smoke with a...

A series of ∼5 nm sized carbon dots (CDs) with different oxygen contents were fabricated and employed as a model material with which to explore the impacts of carbon nanoparticles on rice-plant growth. We show that CDs can penetrate into all parts of rice plants, including the cell nuclei. Systematic investigations provide insight into the different processes by which seed germination, root elongation, seedling length, enzyme (RuBisCO) activity, and carbohydrate generation are increased. CDs are capable of entering the cell, reaching the nucleus, loosening the DNA structure, and increasing the thionin (Os06g32600) gene expression, which finally enhanced the rice-plant disease-resistance ability. CDs can be degraded by plant to form plant-hormone analogues and CO2, and then the hormone analogues promote the rice-plant growth, while the CO2 is converted into carbohydrates through the Calvin cycle of photosynthesis. The outcome of these processes is a 14.8% enhancement of the total rice yield and an increase...

Pneumonia is a kind of inflammation, which can cause high morbidity and mortality, and the treatment of pneumonia has received widespread attention. Heme oxygenase-1 (HMOX1) is a cell protective enzyme and can generate an anti-inflammatory response. Here, we demonstrate that degradable carbon dots (from L-ascorbic acid, CDs-1) can up-regulate the expression of HMOX1 in animal cells and tissues, which has a therapeutic effect on LPS-induced acute lung injury in mice. It was confirmed from in vitro experiments that CDs-1 could significantly up-regulate the expression of mRNA and the protein of HMOX1, which can increase the expression of HMOX1 by 5 times in a short time, decreasing the reactive oxygen species level in a cellular inflammation model induced by LPS. Furthermore, a series of in vivo comparative experiments show that CDs-1 could effectively treat acute lung injury and improve the survival rate of mice to 80%. Our work provides a practical way for the treatment of acute inflammation and the promising application of CDs in anti-inflammation.

At present, the fixation of CO2 always requires it to be extracted from the atmosphere first, which leads to more energy consumption. Thus, direct photoreduction of low-concentration CO2 to useful chemicals (e.g., syngas) under sunlight is significant from an energy-saving and environmentally friendly perspective. Here, the design and fabrication of a [Ru(bpy)3 ]/[Co20 Mo16 P24 ] composite is demonstrated for visible-light-driven syngas production from diluted CO2 (3-20 %) gas with a high yield of approximately 1000 TONs (turnover number of syngas). This activity is an order of magnitude higher than the reported system with [Ru(bpy)3 ]2+ participation. With evidence from ultrafast transient absorption, GC-MS, 1 H NMR spectroscopy and in situ transient photovoltage tests, a clear and fundamental understanding of the highly efficient photoreduction of CO2 by the [Ru(bpy)3 ]/[Co20 Mo16 P24 ] composite is achieved. Making use of the structure and property designable polyoxometalates towards the photo-fixation of CO2 is a conceptually distinct and commercially interesting strategy for making useful chemicals and environmental protection.

Photocatalytic water splitting to produce hydrogen and hydrogen peroxide is the main goal of photocatalysis. However, the reactions of both are water based and thus, it is extremely challenging to conduct both processes on one catalyst. Herein, a function-switchable metal-free catalyst was designed and synthesized through the polycondensation of procyanidin and 4-methoxybenzaldehyde. Impressively, the catalyst developed here not only split water to produce hydrogen via a four-electron reaction process in the absence of air, but also generated hydrogen peroxide by preferentially reducing oxygen via a two-electron pathway in air. The production rates of hydrogen and hydrogen peroxide reached 252.02 and 1385.42 μmol h−1 g−1, respectively. Through in situ transient photovoltage tests and kinetic analysis, a clear and fundamental understanding of the highly efficient and switchable functions was acquired for this photocatalyst. This study highlights the unique behavior and provides an insight into the design of function-switchable catalysts and the regulation of catalytic reactions.

The utilization of solar energy and valid photocatalyst is one of the most effective strategies to achieve water splitting into hydrogen (H2) and oxygen (O2). Although enormous effort has been devoted to photocatalysts, the sunlight still cannot be fully utilized by the developed photocatalysts. It is important but remains challenging to develop a broad spectrum-driven photocatalyst for overall water splitting. Here, we design a UV-Vis-NIR broad spectrum-driven carbon dots modified WO2-NaxWO3 (WO2-NaxWO3-CDs) composite as photocatalyst for overall water splitting without requirement of any sacrificial agents or cocatalysts. When the concentration of CDs in the sample is 0.008 gCDs/gcatalyst, the WO2-NaxWO3-CDs shows the highest photocatalytic activity with stoichiometric ratio of H2/O2 evolutions and their rates are 0.05/0.02, 2.58/1.24, 4.74/2.28 μmol/h under UV (λ 760 nm) light irradiation, respectively. It is also impressive that the photocatalyst shows excellent stability for about 6 cycles of repetitive experiments. The WO2-NaxWO3-CDs composites functioned as broad spectrum-driven photocatalyst for overall water splitting should attribute to the synergistic effect of WO2-NaxWO3 and CDs, in which the WO2-NaxWO3 provides the suitable bandgap, while the CDs can enhance light absorption and accelerate separation efficiencies of photo-generated charge carriers.

Optoelectronic resistive switching (RS) devices are attracting attention due to their promising potential in optical communication technology. In this study, a photo-tunable organic memory device based on poly(4-vinylphenol) (PVP) and N-doped carbon quantum dot nanocomposites is presented. After UV light irradiation, the set voltage of the device can be gradually reduced by adjusting the irradiation time. This memory device presents excellent memory performance after large-angle bending or repetitive bending tests. More importantly, the controlled switching voltage characteristic enabled the realization of encrypted image storage. Raman spectra evidence that a local conductive sp2-hybridized carbon region was generated through UV light reduction, which can effectively enhance the internal electrical field and shorten the tunneling distance between the carbon dots, thus decreasing the set voltage. Our work provides a new approach towards the development of photo-tunable organic memory for future wearable optoelectronic neuromorphic computing systems.

Light irradiation can affect electronic properties of catalysts and the introduction of appropriate light into electrocatalysts may have a significant impact on the electrocatalytic process; however, this has not been fully studied. Herein, we propose a photo-activated process cascaded electrocatalysis for CO2 reduction to produce syngas over a core–shell ZIF-8@Co/C catalyst. Under light irradiation, the onset potential and overpotential of ZIF-8@Co/C positively shift by 40 and 200 mV, and the syngas production is enhanced 5.2-fold at a bias potential of −0.9 V vs. RHE. It is noteworthy that the electric energy efficiency is enhanced by 30%. Deducting syngas generated by electricity, the solar-to-syngas conversion efficiency (joule to joule) is as high as 5.38%, which outperforms reported photoelectrochemical systems. These devices also relatively maintain high efficiency in neutral pH aqueous solution. Dedicated experiments and in situ transient photovoltage studies demonstrate that the cascaded photo-activation of CO2 and H+ in electrocatalysis accounts for the outstanding catalytic performance.

The electrocatalytic carbon dioxide (CO2) reduction reaction (CO2RR) involves a variety of electron transfer pathways, resulting in poor reaction selectivity, limiting its use to meet future energy requirements. Polyoxometalates (POMs) can both store and release multiple electrons in the electrochemical process, and this is expected to be an ideal “electron switch” to match with catalytically active species, realize electron transfer modulation and promote the activity and selectivity of the electrocatalytic CO2RR. Herein, we report a series of new POM-based manganese-carbonyl (MnL) composite CO2 reduction electrocatalysts, whereby SiW12–MnL exhibits the most remarkable activity and selectivity for CO2RR to CO, resulting in an increase in the faradaic efficiency (FE) from 65% (MnL) to a record-value of 95% in aqueous electrolyte. A series of control electrochemical experiments, photoluminescence spectroscopy (PL), transient photovoltage (TPV) experiments, and density functional theory (DFT) calculations revealed that POMs act as electronic regulators to control the electron transfer process from POM to MnL units during the electrochemical reaction, enhancing the selectivity of the CO2RR to CO and depressing the competitive hydrogen evolution reaction (HER). This work demonstrates the significance of electron transfer modulation in the CO2RR and suggests a new idea for the design of efficient electrocatalysts towards CO2RR., Polyoxometalates as electron regulators to promote the carbonyl manganese (MnL) electrocatalyst for highly efficient CO2 reduction in aqueous electrolyte.

The production of hydrogen peroxide (H2O2) by photocatalytic water splitting has attracted much attention due to the wide application of H2O2 as a multi-functional chemical. Most of the present photocatalysts require sacrificial agents and/or noble metal cocatalysts. Herein, we report that phosphorus-doped porous carbon nitride (CPN), as a metal-free photocatalyst, achieves the photocatalytic water splitting via a two-channel pathway (water oxidation reaction and oxygen reduction reaction) with high H2O2 yield of 1968 μmol g−1 h−1 (highest yield in current records without sacrificial agent) under room temperature and normal pressure without sacrificial agent and cocatalyst. The quantum efficiency of the sole production of H2O2 was measured to be 1.57% under wavelength λ = 420 nm and the solar energy conversion efficiency was determined to be 0.43%. In the present reaction system, the concentration of H2O2 can be up to 0.171% (wt%) in a one-batch reaction using 80 mg CPN catalyst (in 15 mL oxygen saturated H2O) after 36 h under visible light illumination. H2O2 obtained by this metal-free catalyst without adding a sacrificial agent is more conducive to subsequent purification in industrial production.

Controlling interface gas adsorption properties of carbon materials is a prerequisite for exploiting efficient metal-free electrocatalysts but it is usually ignored. Herein, we fabricate a hierarchical porous carbon electrocatalyst with defect (DHPC) by carbon thermal reaction, which shows good CO2RR selectivity and stability. The experimental results indicated that the carbon defect might be the active center for efficient CO2RR performance because it can serve as a Lewis base center and provide an appropriate CO2-chemisorption energy. Moreover, X-ray absorption spectroscopy (XAS) results demonstrated that the carbon defect can induce a reversible carbon–carbon interface with CO2 gas molecule, which would be further strengthened under an applied bias. Besides, the 13CO2 isotope labelling experiment and density functional theory calculations further confirmed that the high CO2RR performance of DHPC comes from its intrinsic defect sites. This study not only provides a new avenue and concept to design CO2RR electrocatalysts but also, to some extent, indicates a possible catalytic mechanism for carbon defect-based electrocatalysts.

Heat-localized evaporation has been perceived as a potential strategy for water purification. However, the evaporators reported usually suffer from poor performances under low solar irradiation which is nevertheless very common in daily life, and the study on the interfacial thermodynamics still needs further exploration. By imitating the structure of natural leaves, we fabricate a foldable carbon-dot-based evaporator which achieves an excellent vapor generation performance of 1.58 kg m−2 h−1 under 0.5 sun irradiation, significantly higher than those of other evaporators reported previously. Moreover, its performance could be further enhanced up to 2.18 kg m−2 h−1 by being fabricated into a 3D structure, which can be possibly attributed to an extra environmental heat input because of its relatively low interfacial temperature according to our theoretical model. In addition, the large-scale production of the evaporator is greatly facile in terms of raw materials and the fabrication procedure. Finally, this energy from weak solar irradiation and environmental heat could also be efficiently converted into gravitational potential by integrating our steam generator with a forward osmosis system to drive water vertical transportation, promising for the full utilization of low-grade energy.

Solar steam generation has drawn great interest to partially remedy water crisis issues, especially in remote areas with water scarcity that have plenty of seawater (such as survival in the wild on islands surrounded by sea) by utilizing renewable solar energy to evaporate seawater. Evaporators with high evaporation rates have been widely reported recently, though efforts have rarely focused on the improvement of the mechanical properties of photo-thermal active materials with which to develop a mechanically robust and durable evaporator with high performance, thus severely limiting their widespread applications. Additionally, the effect of evaporator microstructures has not been quantitatively analyzed, which is otherwise a necessary guideline to further boost areal evaporation performance. Herein, a robust carbon dot (CD)-based evaporator was designed from the nanometer to micrometer scale by loading nano-sized CDs onto microporous substrates, which shows a high evaporation performance of up to 2.31 kg m−2 h−1 (under one sun illumination) by fully capturing solar energy and extra environmental heat. While maintaining good performance, the CD-loaded evaporator shows excellent deformation tolerance derived from strong interfacial adhesion between the CDs and cellulose, meaning that it can be bent, folded, twisted, and even sonicated without obvious damage, indicating great convenience for packing and transportation. Then, contributed to by its outstanding mechanical properties, an evaporator with a 3D structure on the millimeter scale was therefore constructed through origami, which reaches a high evaporation rate of 2.93 kg m−2 h−1 under one sun illumination. Besides this, this evaporator can be easily manufactured at low cost without needing any sophisticated preparation procedure or strict conditions, holding promise for large-scale applications and commercialization. Finally, we propose a theoretical model to simulate the effect of the microstructure on the performance of the solar evaporator in terms of the evaporation area, which is in accordance with the experimental results, providing quantitative insight for the structural engineering of solar evaporators in the future.

Quantum dots (QDs) represent one of the most promising photocatalytic systems for solar hydrogen production. Tremendous works have been devoted to the design of QDs photocatalysts, but their further development is limited by the unwanted mix of high- and low-quality QDs with different activities. With multinary Ag-In-Zn-S (AIZS) QDs as an example, here, we present a simple method for the extraction and screening of efficient photocatalysts by combination of gradient centrifugation and electrochemiluminescence (ECL). With controllable introduction of poor solvent, the crude QDs were separated into five individual samples by gradient centrifugation, from which ECL tests were performed to get the surface state information for photocatalyst screening. By the combination of size-selective centrifugation and ECL screening, we were able to get the high-activity component (AIZS-#4), which achieved 1.68 mmol·g–1 h–1, 6 times higher than that of the initial AIZS QDs. This work provides an alternative useful pathway...

Carbon dots (CDs) are an emerging subset of nanomaterials, defined by characteristic sizes of

I–III–VI quantum dots (QDs) play an important role in visible-light-driven photocatalysis due to their unique optical properties and widely tunable bandgap. However, these materials suffer from rich defect states and high charge carrier recombination. In this work, a facile mixed-ligand method was developed for the manipulation of the optical and photocatalytic properties of multinary Ag–In–Zn–S QDs by introducing 3-mecaptopropionic acid (MPA) into the l-cysteine (Cys) capped QDs system during synthesis. The effect and mechanism of MPA addition was systematically investigated. With the increase of MPA/Cys, the photoluminescence (PL) quantum yield (QY) of the QDs shows an obvious increase at the first stage (MPA/Cys

Here, we show the fabrication of the carbon dots (CDs) with green and orange emissions from PTCDA (perylene-3,4,9,10-tetracarboxylic dianhydride). Using these CDs as emitters, the orange (or green) CDs LEDs were fabricated, which show electroluminescence (EL) spectra centered at 560 nm (or 498 nm) with an external quantum efficiency (EQE) of 1.98 % (1.76 %) adhering a luminescence of 626 cd m-2 (or 519 cd m-2 ). The machine learning was successfully used to predict PL CCT value. With the model, the white photoluminescence (PL) emission with adjustable correlated color temperature (CCT) from 3093 to 11018 K via combining blue, green, and orange CDs was achieved. Then, we obtained the warm white CDs LEDs with CCT of 3107, 4071 and 4548 K, and cold white CDs LEDs with CCT of 5632 (CIE coordinates of (0.33, 0.33), EQE: 1.18 %, luminescence: 598 cd m-2 ) and 6034 K accurately.