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[Display omitted] Despite great efforts that have been made, photocatalytic carbon dioxide (CO 2) reduction still faces enormous challenges due to the sluggish kinetics or disadvantageous thermodynamics. Herein, cadmium sulfide quantum dots (CdS QDs) were loaded onto carbon, oxygen-doped boron nitride (BN) and encapsulated by titanium carbide (Ti 3 C 2 , MXene) layers to construct a ternary composite. The uniform distribution of CdS QDs and the tight interfacial interaction among the three components could be achieved by adjusting the loading amounts of CdS QDs and MXene. The ternary 100MX/CQ/BN sample gave a productive rate of 2.45 and 0.44 μmol g-1 h−1 for carbon monoxide (CO) and methane (CH 4), respectively. This CO yield is 1.93 and 6.13 times higher than that of CdS QDs/BN and BN counterparts. The photocatalytic durability of the ternary composite is significantly improved compared with CdS QDs/BN because MXene can protect CdS from photocorrosion. The characterization results demonstrate that the excellent CO 2 adsorption and activation capabilities of BN, the visible light absorption of CdS QDs, the good conductivity of MXene and the well-matched energy band alignment jointly promote the photocatalytic performance of the ternary catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] Photocatalytic reduction of carbon dioxide (CO 2) into fuels is an auspicious route to alleviate the energy and environmental crisis brought by the continuous depletion of fossil fuels. The CO 2 adsorption state on the surface of photocatalytic materials plays a significant role in its efficient conversion. The limited CO 2 adsorption capacity of conventional semiconductor materials inhibit their photocatalytic performances. In this work, a bifunctional material for CO 2 capture and photocatalytic reduction was fabricated by introducing palladium (Pd)-copper (Cu) alloy nanocrystals onto the surface of carbon, oxygen co-doped boron nitride (BN). The elemental doped BN with abundant ultra-micropores had high CO 2 capture ability, and CO 2 was adsorbed in the form of bicarbonate on its surface with the presence of water vapor. The Pd/Cu molar ratio had great impact on the grain size of Pd-Cu alloy and their distribution on BN. The CO 2 molecules tended to be converted to carbon monoxide (CO) at interfaces of BN and Pd-Cu alloys due to their bidirectional interactions to the adsorbed intermediate species while methane (CH 4) evolution might occur on the surface of Pd-Cu alloys. Owing to the uniform distribution of smaller Pd-Cu nanocrystals on BN, more effective interfaces were created in the Pd 5 Cu 1 /BN sample and it gave a CO production rate of 7.74 μmolg−1h−1 under simulated solar light irradiation, higher than the other PdCu/BN composites. This work can pave a new way for constructing effective bifunctional photo-catalysts with high selectivity to convert CO 2 to CO. [ABSTRACT FROM AUTHOR]

[Display omitted] Membranes based on transition metal carbides/nitrides (MXenes) have significant water treatment potential because of their unique molecular sieving properties and excellent permeation performance. However, hydrophilic MXenes swell upon water immersion, and improving their stability remains challenging. In this study, a Fe3+–tannic acid (TA) complex was used as a cross-linker and surface modifier to prepare high-performance titanium carbide (Ti 3 C 2 T x) MXene laminar membranes. Fe3+–TA formation on the nanosheets increased the interlayer spacing and stabilized the laminar structure. The membrane with the highest performance among the as-prepared membranes exhibited a high water permeance of 90.5 L/m−2(−|-)h−1 bar−1 (which is twice that of the pristine Ti 3 C 2 T x membrane) and good separation efficiency (methyl blue rejection rate: ∼99.8 %; Na 2 SO 4 rejection rate: ∼5.0 %). Furthermore, the Fe3+–TA complex enhanced the membrane hydrophilicity, resulting in excellent antifouling properties. This study provides an environmentally friendly and facile method for fabricating two-dimensional loose nanofiltration membranes for textile wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] Membranes based on transition metal carbides/nitrides (MXenes) have significant water treatment potential because of their unique molecular sieving properties and excellent permeation performance. However, hydrophilic MXenes swell upon water immersion, and improving their stability remains challenging. In this study, a Fe3+–tannic acid (TA) complex was used as a cross-linker and surface modifier to prepare high-performance titanium carbide (Ti 3 C 2 T x) MXene laminar membranes. Fe3+–TA formation on the nanosheets increased the interlayer spacing and stabilized the laminar structure. The membrane with the highest performance among the as-prepared membranes exhibited a high water permeance of 90.5 L/m−2(−|-)h−1 bar−1 (which is twice that of the pristine Ti 3 C 2 T x membrane) and good separation efficiency (methyl blue rejection rate: ∼99.8 %; Na 2 SO 4 rejection rate: ∼5.0 %). Furthermore, the Fe3+–TA complex enhanced the membrane hydrophilicity, resulting in excellent antifouling properties. This study provides an environmentally friendly and facile method for fabricating two-dimensional loose nanofiltration membranes for textile wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] The incipient wetness impregnation (IWI) method is widely used in the preparation of supported transition metal catalysts for its high throughput and cost-effective synthesis, yet suffers from poor metal-support interaction, restricting its further application at an industrial scale. Herein, a universal strategy of chelation coupled impregnation (CCI) is presented. The as-prepared Ni/CeO 2 (CCI) showed superior catalytic performance for CO 2 conversion (84.3%) and CH 4 selectivity (100%) under the experimental conditions (WGHSV = 24,000 mL g−1 h−1 and H 2 /CO 2 = 4:1) even at low temperatures (T = 275 °C). The surface characterization results confirmed that the agglomeration of metal active sites in Ni/CeO 2 (CCI) was restricted and more surface oxygen vacancies were generated on CeO 2. Further, the in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) analysis suggested that the surface oxygen vacancies that served as active sites could facilitate the direct dissociation of CO 2 more favorably than the associative route, thus significantly promoting CO 2 methanation activity. [ABSTRACT FROM AUTHOR]

Monolithic wood carbon armed with mesoporous nickel-silica nanocomposite layer is a stiff and highly efficient catalyst for toluene steam reforming. [Display omitted] • A thin Ni-silica layer was in-situ grown on the wall of wood carbon channels. • Small Ni nanoparticles are embedded in mesoporous silica with carbon protection. • The hardness and hydrothermal stability of monolithic wood carbon was improved. • The multilevel pore structure enhances mass transfer and avoids coke deposition. • The monolithic catalyst exhibits excellent tar steam reforming performance. Steam reforming is an effective measure for biomass tar elimination as well as H 2 -rich syngas (H 2 + CO) production. However, the granular or powdery Ni-based catalysts are prone to deactivation, which is caused by inappropriate mass transfer and clogging of catalyst bed. Herein, monolithic wood carbon (WC) with low-tortuosity microchannels is armed with a carbon-coated mesoporous nickel-silica nanocomposite (Ni-SiO 2 @C) layer via an evaporation-induced self-assembly and calcination procedure for toluene (tar model compound) steam reforming. The quality of the Ni-SiO 2 @C layer growing on the surface of WC microchannel is affected by the molar ratios of Si/Ni feed. A uniform thin-layer coverage is obtained on the Ni-15SiO 2 @C/WC (Si/Ni = 15) catalyst, where highly dispersed Ni nanoparticles (average size of 6.6 nm) with appropriate metal-support interaction and remarkable mechanical strength are achieved. The mass transfer, coke resistance, and hydrothermal stability of the Ni-15SiO 2 @C/WC catalyst were significantly improved by the multilevel structure assembled from the WC microchannels and the secondary ordered SiO 2 mesopores. A stable toluene conversion over 97% with an H 2 yield of 135 μmol/min was obtained at 600 °C on the Ni-15SiO 2 @C/WC catalyst. This work opens a new window for facilely constructing high-performance wood carbon-based monolithic tar reforming catalyst. [ABSTRACT FROM AUTHOR]

A mitochondria targetable antioxidants based on selenium-doped carbon nanodots with two photon fluorescence and efficient scavenging ability was fabricated. • TPP-Se-CDs with two-photon blue fluorescence, high colloidal stability, and redox-responsive fluorescence were synthesized. • TPP-Se-CDs exhibited low cytotoxicity and mitochondria targeting ability. • TPP-Se-CDs can suppress H 2 O 2 and phorbol 12-myristate 13-acetate induced elevated ROS levels within mitochondria. Mitochondrial oxidative stress is associated with the occurrence and development of a wide range of human diseases. The development of methodologies to alleviate oxidative stress-mediated injury may have therapeutic potential. Herein, we report the design and preparation of triphenylphosphonium-functionalized selenium-doped carbon nanodots (TPP-Se-CDs) that can efficiently scavenging hydroxyl radicals (OH) and superoxide anions (O 2 −) in mitochondria region. Se-CDs with two-photon blue fluorescence were initially prepared by facile hydrothermal treatment of selenomethionine, followed by the covalent conjugation with TPP. The as-obtained TPP-Se-CDs showed high colloidal stability, strong scavenging abilities towards OH and O 2 −. Moreover, TPP-Se-CDs exhibited low cytotoxicity and mitochondria targeting ability. Taking advantages of these prominent features, TPP-Se-CDs have been successfully applied to combat H 2 O 2 and phorbol 12-myristate 13-acetate (PMA) induced oxidative stress in mitochondria. [ABSTRACT FROM AUTHOR]

A 3D flower-like mesoporous Ce doped ZnO composite composed of nanosheets was prepared by a facile, one-step wet chemical method at room temperature. It was found that the moderate Ce doping can improve the light absorption of ZnO. The photocatalytic activities of the samples were studied by the degradation of Rhodamine B (RhB) and phenol under stimulated sunlight. The 1% mole ratio of Ce doped ZnO composites (denoted as CZ1) showed higher photocatalytic performance than other samples, where 85.1% of RhB and 69.6% of phenol can be removed within 125 min and 120 min, respectively. The Ce4+ doped in the lattice of ZnO can act as the electron trapping sites, which effectively improve the electron-hole separation. In addition, it was also found the annealing temperature had effect on the morphology and structure of Ce doped ZnO. The photocatalytic performance can be further enhanced at proper annealing temperature (500 °C) due to the increase of ZnO crystallinity with maintained flower-like structure and the formation of CeO 2 -ZnO heterojunction at their tight interface promoting the separation of photogenerated electron-hole pairs. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, three artificial light-harvesting systems are constructed by a supramolecular approach in aqueous environment. The water-soluble bipyridinium derivatives (DPY1, DPY2, and DPY3) were self-assembled with cucurbit[7]uril (CB[7]) to form the host–guest DPY-CB[7] complexes, which can highly disperse in water as small nanoparticles. The excited DPY-CB[7] assemblies can transfer energy to the sulfo-rhodamine 101 (SR101) molecules at a high donor/acceptor ratio. With the help of hydrophobic cavity of CB[7], the DPY-CB[7] + SR101 systems can works as a nanoreactor for effective dehalogenation of α -bromoacetophenone and its derivatives in aqueous medium under white light irradiation. Such light-harvesting systems has greatly potential applications to realize some organic photocatalytic synthesis in aqueous environment. [ABSTRACT FROM AUTHOR]

Iodine is employed firstly as pore-making agent for starch-based materials. [Display omitted] High specific surface area, hierarchical porosity, high conductivity and heteroatoms doping have been considered as the dominating factors of high-performance carbon-based supercapacitors. Inspired by the blue phenomenon of combination of starch and iodine, iodine is employed firstly as pore-making agent to create micropores for the starch-derived carbon in this study. Based on this mechanism, the hierarchically porous carbon is synthesized through simple solvent heating and high-temperature (1000 °C) carbonization, which achieves high specific surface area of 2989 m2 g−1 (an increase of 39.7% compared to that without iodine) and low electrical resistivity of 0.21 Ω·cm. The assembled symmetric supercapacitors, combined with dual redox-active electrolyte (Bi3+ and Br−), deliver the specific capacitance of 1216 F g−1, energy density of 65.4 Wh kg−1, as well as power density of 787.3 W kg−1 at 2 A g−1. In brief, the abundant biomass resource starch is exploited as carbon source, and the iodine sublimation reaction is conducted to provide more micropores to develop high-performance electrodes of supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The NO reduction to NH 3 process is constrained by thermodynamic processes on single-atom catalysts (SACs) and electrochemical processes on double-atom catalysts (DACs). • Single Cu atom doped graphdiyne (Cu@GDY) exhibits the optimal NORR catalytic activity with the lowest thermodynamic energy barriers of 0.10 eV. • A catalytic activity relationship is established between the d-band centers of the SACs, DACs and NORR performance. • Thermodynamic and electrochemical processes of NORR are regulated by d-band center of catalysts. The electrocatalytic conversion of nitric oxide (NORR) to ammonia (NH 3) represents a pivotal approach for sustainable energy transformation and efficient waste utilization. Designing highly effective catalysts to facilitate the conversion of NO into NH 3 remains a formidable challenge. In this work, the density functional theory (DFT) is used to design NORR catalysts based on single and double transition metal (TM:Fe, Co, Ni and Cu) atoms supported by graphdiyne (TM@GDY). Among eight catalysts, the Cu 2 @GDY is selected as a the most stable NORR catalyst with high NH 3 activity and selectivity. A pivotal discovery underscores that the NORR mechanism is thermodynamically constrained on single atom catalysts (SACs), while being governed by electrochemical processes on double atom catalysts (DACs), a distinction arising from the different d- band centers of these catalysts. Therefore, this work not only introduces an efficient NORR catalyst but also provides crucial insights into the fundamental parameters influencing NORR performance. [ABSTRACT FROM AUTHOR]

The CrB and MnB doped graphdiyne (CrB@GDY and MnB@GDY) electrocatalysts were screened out from 27 candidates with low thermodynamic energy barriers and high selectivity for urea synthesis based on a new four-step screening strategy. [Display omitted] • Thermodynamic stability, hydrogenation and C N coupling process are used to screen double-atom catalysts for urea synthesis. • CrB@GDY and MnB@GDY exhibited low thermodynamic energy barriers of 0.41 eV and 0.66 eV for urea synthesis, respectively. • Established a catalytic activity relationship between the d-band center of the double-atom catalysts and urea performance. • CrB@GDY and MnB@GDY can suppress the side reactions (CO 2 RR, NRR). Electrocatalytic C N coupling using nitrogen (N 2) and carbon dioxide (CO 2) as precursors offers a promising alternative for urea production under mild conditions, compared to traditional synthesis approaches. However, the design and screening of extremely efficient electrocatalysts remains a significant challenge in this field. Hence, we propose a systematic approach to screen efficient double-atom catalysts (DACs) with both metal and boron active sites, employing density functional theory (DFT). A comprehensive evaluation of 27 potential catalysts were performed, taking into account their stability, co-adsorption of N 2 and CO 2 , as well as the potential-determining step (PDS) involved urea formation. The calculated results show that co-doped graphdiyne with CrB and MnB double atoms (CrB@GDY and MnB@GDY) emerge as potential electrocatalysts for urea production, displaying thermodynamic energy barriers of 0.41 eV and 0.66 eV, respectively. More importantly, these two DACs can significantly suppress the ammonia (NH 3) and C 1 products formation. Furthermore, a catalytic activity relationship between the d -band centers of the DACs and urea production performance were established. This study not only forecasts two promising DACs for subsequent experimental work but also establishes a theoretical framework for the evaluation of DACs in electrocatalytic urea synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] Urea is ubiquitous in agriculture and industry, but its production consumes a lot of energy. The conversion of nitrogen (N 2) and carbon dioxide (CO 2) into urea via an electrocatalytic C N coupling reaction under ambient conditions would be a major boon to sustainable development. However, designing a metal − free catalyst with high activity and selectivity for urea remains a major challenge. Herein, by means of density functional theory (DFT) and ab − initio molecular dynamics (AIMD) computations, the B 12 cluster doped on nitrogenated graphene (C 2 N) substrate catalyst (B 12 @C 2 N) with superior stability was designed for electrocatalytic urea synthesis starting from the CO 2 and N 2 through four reaction mechanisms. The nature of the co-adsorption activation of CO 2 and N 2 on the B 12 @C 2 N catalyst was investigated, the electrochemical proton − electron transfer steps and the C N thermochemical coupling led to the synthesis of urea. The study showed that the B 12 @C 2 N catalyst exhibited high catalytic activity for urea synthesis with the lowest limiting potential of − 1.01 V following the *HNNH mechanism compared with other mechanisms. The potential − determining step (PDS) is the formation of the *CO+*NH 2 NH 2 species. However, the two − step C N coupling barriers of *NCON species are 0.13 eV and 0.60 eV using AIMD and a "slow − growth" sampling approach in an explicit water molecules model. Calculations also showed that the byproducts of carbon monoxide (CO), methane (CH 4), methanol (CH 3 OH), ammonia (NH 3), and hydrogen (H 2) can be inhibited on the B 12 @C 2 N catalyst. Therefore, the metal − free catalyst not only has a good performance for the hydrogenation of CO 2 and N 2 promoting the electrochemical reaction, but also facilitates C N thermochemical coupling for urea synthesis. This work provides new insights into the synthesis of urea via the C N coupling reaction on a metal − free electrocatalyst, a process that could contribute to greenhouse gas mitigation to help meet carbon neutrality targets. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile method was developed for synthesis of deep-red emissive CDs. • The CDs with a narrow full width at half maximum of 19 nm showed a high fluorescence quantum yield of 24.7%. • Pdots encapsulated with the CDs exhibited low cytotoxicity, good biocompatibility, and ER-targeting ability. • Pdots encapsulated with the carbon nanodots can be used for sensitive and selective detection of Cu2+ in biosystems. Endoplasmic reticulum (ER) is the largest organelle in eukaryotic cells and plays a variety of functions in living cells include protein folding, calcium homeostasis, and lipid biosynthesis. Normal function of ER is crucial for cell survival, while disequilibrium of ER can cause misfolding of proteins and ER stress, leading to many serious diseases. It has been documented that ER stress is closely related to the metabolism of Cu2+, as ER is the main intracellular accumulation space of Cu2+ and toxic reactive oxygen species can be generated by Cu2+ via Fenton and Haber-Weiss reactions. In this context, developing a powerful tool capable of selective and sensitive monitoring of Cu2+ in ER and investigating its role in physiological and pathological processes is of great importance. Herein, we report the first ER targeted near infrared (NIR) nanosensor, polymer dots encapsulated with NIR hydrophobic carbon nanodots, for detecting Cu2+ in biosystems. This nanosensor with stable fluorescence showed a fast response toward Cu2+ (120 s) and can be used for the quantification of Cu2+ in a linear range covering from 0.25 to 9.0 μM with a detection limit of 13 nM. In addition, the fluorescence variations of the nanosensor are remarkably specific to Cu2+ in comparison with the other metal ions and amino acids. Moreover, the developed nanosensor exhibited low cytotoxicity, good biocompatibility, and ER targeting ability. Because of these excellent spectroscopic features, the nanosensor was successfully utilized for visualizing Cu2+ fluctuations at the living cell, zebrafish and mouse levels, which further proved its potential application in biological systems. [ABSTRACT FROM AUTHOR]

[Display omitted] The electrochemical carbon dioxide (CO 2) reduction reaction (CO 2 RR) used for converting higher-value chemicals is a promising solution to mitigate CO 2 emissions. Nickel (Ni)-based catalysts have been identified as a potential candidate for CO 2 activation and conversion. However, in the CO 2 RR, the size effect of the Ni-based electrocatalysts has not been well explored. Herein, the single Ni atom and the Ni 4 cluster doped nitrogen-doped carbon nanotube (Ni@CNT and Ni 4 @CNT), and the Ni (1 1 0) facet were designed to explore the size effect in the CO 2 RR by using density functional theory (DFT) calculations. The results show that carbon monoxide (CO) is produced on the Ni@CNT with a free energy barrier of 0.51 eV. The reduction product of CO 2 on the Ni 4 @CNT and Ni(1 1 0) facet is methane (CH 4) in both cases, via different reaction pathways, and the Ni(1 1 0) facet is a more efficient electrocatalyst with a low overpotential of 0.27 V when compared to Ni 4 @CNT (0.50 V). The rate-determining step (RDS) is the formation of *CHO on the Ni 4 @CNT (The "*" represents the catalytic surface), while the *COH formation is the RDS on the Ni(1 1 0) facet. Meanwhile, the Ni(1 1 0) facet also has the highest selectivity of CH 4 among the three catalysts. The CO 2 reduction product changes from CO to CH 4 with the increasing size of the Ni-based catalysts. These results demonstrate that the catalytic activity and selectivity of CO 2 RR highly depend on the size of the Ni-based catalysts. [ABSTRACT FROM AUTHOR]

This work developed a facile strategy for constructing highly porous carbon materials from porous organic materials synthesized by three isomers of triphenyl. The boosted surface area and microporosity endow these materials with significant CO 2 uptake capacity as high as 7.78 mmol g−1 at 273 K and 1 bar, thus resulting in appealing potential for CO 2 adsorption and separation. [Display omitted] • Porous carbon materials featuring abundant microporous textures are synthesized from porous organic polymers. • These porous carbon materials possess surface areas as high as 3367 m2 g−1 and pore volumes up to 1.224 cm3 g−1. • PCM-O700 exhibits a CO 2 capacity of 7.78 mmol g−1 at 273 K and 1 bar. • These materials are capable of selective adsorption of CO 2 over N 2. The increase in atmospheric carbon dioxide (CO 2) concentration has led to numerous problems related to our living environment, seeking an efficient carbon capture and storage (CCS) strategy associated with low energy consumption and expenditures is highly desirable. Here, we demonstrate a facile approach to synthesize a series of highly porous carbon materials derived from porous organic polymers synthesized from three low-cost isomers of triphenyl using chemical activation with KOH at different temperatures. Compared with the precursor porous organic polymers, the porosity of the prepared porous carbon materials is significantly enhanced with surface areas as high as 3367 m2 g−1 and pore volumes up to 1.224 cm3 g−1. Notably, such porous carbon materials deliver an exceptionally high CO 2 adsorption capacity of 7.78 mmol g−1 at 273 K and 1 bar, a value that is superior to most of the previously reported adsorbents. In addition, these porous organic polymers and derived porous carbon materials exhibit high CO 2 /N 2 selectivity at ambient conditions. Therefore, the facile construction of highly porous carbon materials from porous organic polymers may offer an efficient strategy for CO 2 adsorption and separation and further mitigates greenhouse effect. [ABSTRACT FROM AUTHOR]

[Display omitted] Constructing effective interphase boundary is one of the efficient approaches for improving photocatalytic performances of semiconductor materials. In this work, an anatase/rutile-TiO 2 (AR-TiO 2) heterophase junction with appropriate carbon content was successfully fabricated via an in-situ phase transformation process. The phase transformation started from the inner core of the nanoparticles and the area of phase interface between anatase and rutile was carefully controlled by regulating the activation temperature. The well-established type-II band alignment between two TiO 2 phases with residual carbon as additional charge transfer intermediary which significantly improved the light-harvesting and photoinduced electron-hole pair separation. As a result, the optimal AR-TiO 2 -550 catalyst (without adding commonly used Pt as co-catalyst) remarkably enhanced photocatalytic H 2 generation (201 μmol h−1 g−1), which was about 12-fold to that of P25. The AR-TiO 2 -550 heterophase junction also showed long-term stability under simulated solar light irradiation. This research provides a new phase engineering route for developing high-efficient photocatalysts. [ABSTRACT FROM AUTHOR]

Sufficient and well-distributed active sites and highly conductive carbon matrix are two important factors to achieve highly efficient electrocatalysts. In this study, we report an adjusted metal-organic frameworks (MOF)-based route for the preparation of nitrogen-doped Fe/Co bimetallic electrocatalysts. With suitable Fe/Co molar ratio (Fe/Co = 1/4.15), Co nanoparticles (NPs) with mild oxidation state and Co 3 Fe 7 alloys wrapped with thin graphene layers are embedded in an integrated and continuous carbon network. The corresponding FC@NCs-4.15 catalyst exhibits excellent oxygen reduction reaction (ORR) activity (onset potential (E onset) of 0.94 V and half-wave potential (E 1/2) of 0.84 V vs RHE) in alkaline medium, close to commercial Pt/C and superior to the other two FC@NCs. The desirable ORR performance results from the uniform distribution Co 3 Fe 7 active sites, electron density modification from Co NPs to surrounding carbon layers, hierarchical pore structure with large surface area, low carbon content, high pyridinic and graphitic N components. The FC@NCs-4.15 also displays satisfactory methanol crossover tolerance and durability. [ABSTRACT FROM AUTHOR]

A simple one-step preparation of biomass derived carbon materials with hierarchical pore structure for supercapacitor application is proposed. Briefly, potassium citrate is loaded onto poplar catkin, a forestry and agricultural residue, for carbonization at different temperature (750–900 ℃). With the confined effect of poplar catkin and pore-forming role of potassium compounds, interconnected carbon networks combining of macropores, small mesopores and micropores are obtained. The product carbonized at 850 ℃ (S-850) processes large surface area of 2186 m2/g with two main micropore ranges distributed in 0.5–0.7 nm and 0.7–1.5 nm, and the sample of S-900 processes relatively high electrical conductivity because of the high degree of graphitization. The electrodes based on these carbon materials show main electrical double-layer capacitors with small part of pseudo-capacitors due to O-doping. The S-850 sample displays superior specific capacity at low charge–discharge current density while the electrode based on S-900 shows high specific capacity under high current density. The symmetrical devices based on S-850 give a superb stability and high energy and power densities in alkaline electrolyte. Within a voltage window of 1.4 V, the device can deliver a 13.3 Wh/kg energy density at a power density of 720 W/kg and maintain 7.8 Wh/kg at 14040 W/kg. [ABSTRACT FROM AUTHOR]

Cost-effective electrocatalysts with excellent oxygen reduction reaction (ORR) activity are requisite for the commercial application fuel cells and zinc-air batteries. Herein, we prepare a series of carbon-based non-precious metal catalysts by simply carbonizing the mixture of FeCo-ZIF, melamine and soya-bean oil. The microstructure and electrochemical activity of the prepared catalysts highly depend on the adding amount of FeCo-ZIF. With proper addition, the FeCo-ZIF are transformed into Co 5.47 N and Co 0.72 Fe 0.28 alloy nanoparticles, which are embedded in the in situ formed carbon network consisted of nitrogen-doped graphene-like carbon nanosheets and interwoven carbon nanotubes. The resulted catalyst (FeCo@NCs-0.15) with considerable specific surface area and high pore volume demonstrates a superior ORR catalytic activity than commercial Pt/C with a half-wave potential (E 1/2) of 0.83 V (vs. RHE), onset potential (E onset) of 0.97 V (vs. RHE) and 4-electron dominated reaction path. The durability and methanol resistance are also better than that of commercial Pt/C in alkaline solution. This study provides an inexpensive, facile and scalable strategy to simultaneously realize non-precious metal-based active sites, nitrogen-doping, porosity and highly conductive carbon matrix in one electrocatalyst by one step. [ABSTRACT FROM AUTHOR]