A Thermally Decomposable Template Route to Synthesize Nitrogen-Doped Wrinkled Carbon Nanosheets as Highly Efficient and Stable Electrocatalysts for the Oxygen Reduction Reaction

We successfully developed a thermally decomposable template route to prepare wrinkled carbon nanosheets with a high level of nitrogen functional moieties by direct carbonization of biomass glucose and dicyandiamide as the renewable feedstocks. Confined pyrolysis of glucose within the interlayers of dicyandiamide-derived g-C₃N₄ as a thermally removable template results in the formation of two-dimensional (2D) wrinkled carbon nanosheets as well as simultaneous high-level nitrogen doping. The textural properties and nitrogen contents could be controlled by adjusting the mass ratio of glucose/dicyandiamide. Among various samples, the sample prepared with the dicyandiamide/glucose mass ratio of 7/1 has optimal activity for the electrocatalytic oxygen reduction (onset potential −0.12 V vs saturated calomel electrode (SCE); limiting current density 4.73 mA/cm²) in 0.1 M KOH solution, the half-wave potential of which is only 67 mV larger than that for 20 wt % Pt/C. Moreover, it demonstrates a highly efficient four-electron reaction process, as well as superior durability and tolerance to MeOH crossover to Pt/C. The excellent activity is mainly attributed to the high content of pyridinic and graphitic-N groups, highly graphitized structures, and wrinkled 2D nanostructures, efficiently promoting the increased exposure of actives sites and fast mass/electron transfer

Fluorinated Thieno[2,3:4,5]benzo[1,2d][1,2,3]triazole: New Acceptor Unit To Construct Polymer Donors

A new acceptor unit, fluorinated thieno­[2′,3′:4,5]­benzo­[1,2-d]­[1,2,3]­triazole (fBTAZT), has been designed and synthesized to build two donor–acceptor (D–A) copolymers with the none/fluorinated benzodithiophene (BDT) unit, which have been applied as the electron-donating material with ITIC as an electron-accepting material to fabricate the nonfullerene polymer solar cells (PSCs). It is found that fluorination at the BTAZT unit and BDT unit exerts a significant influence on photophysical properties and photovoltaic performances of the PSCs. As a result, when the fluorine atom is introduced both into the BTAZT unit and the side-chain thiophene ring of the BDT unit, the corresponding polymer PfBTAZT-fBDT exhibits deeper highest occupied molecular orbital–lowest unoccupied molecular orbital energy level and shows stronger interchain interaction with a little broad and red-shift absorption and high charge mobilities as well as good phase-separated morphologies, thus leading to higher power conversion efficiency of 6.59% in nonfullerene PSCs compared with another polymer PfBTAZT-BDT without F atom at the BDT unit, indicating that fBTAZT can be acted as a medium strong organic acceptor to build D–A polymer donor for high efficient PSCs

Nonfullerene Acceptor with “Donor–Acceptor Combined π‑Bridge” for Organic Photovoltaics with Large Open-Circuit Voltage

In this work, a kind of “donor–acceptor (D–A) combined π-bridge” based on the regioselective reactivity of monofluoro-substituted benzothiadiazole (FBT) to link a thiophene ring has been designed to construct a new A−π–D−π–A-type small molecular acceptor (IDT-FBTR) with indacenodithiophene (IDT) as a central core (D) and 3-octyl-2-(1,1-dicyanomethylene)­rhodanine as an electron-withdrawing terminal group (A). Because of the strong intramolecular push–pull electron effect, the IDT-FBTR shows a strong and broad intramolecular charge-transfer absorption band in the range of 500–750 nm. Especially, as an electron-deficient FBT unit (A′) and an electron-rich thiophene ring (D′) in “D–A combined π-bridge” exert an “offset effect” to regulate the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy levels of the molecule, a relatively high LUMO energy level can be maintained for IDT-FBTR that is helpful to enhance the open-circuit voltage (<i>V</i>_oc) for highly efficient organic solar cells (OSCs). Therefore, the optimized OSC device based on IDT-FBTR as the acceptor and PTB7-Th as the donor shows a much high <i>V</i>_oc of 1.02 V with a relatively low <i>E</i>_loss of 0.56 eV and a best power conversion efficiency of 9.14%

Synthesis of Nitrogen-Doped Porous Carbon Spheres with Improved Porosity toward the Electrocatalytic Oxygen Reduction

In this study, a series of activated N-doped porous carbon spheres (ANCSs) have been prepared from biomass as the carbon source to be used as highly active and stable electrocatalysts toward the electrocatalytic oxygen reduction reaction (ORR). Hydrothermal carbonization of biomass glucose, which obtains uniform carbon nanopsheres, is followed by doping N atoms by treatment in ammonia and subsequent activation treatment to form ANCSs. The resultant ANCSs possess a large specific surface area of up to 2813 m²/g and pore volume of up to 1.384 cm³/g, and adjustable N contents (2.38–4.53 atom %) with increasing activation temperature. The graphitic and pyridinic-N groups dominate in various N functional groups in the ANCSs. Remarkably, the 1000 °C-activated sample demonstrates competitive activity and outstanding stability and methanol crossover toward the ORR with a four-electron transfer pathway in alkaline media compared to commercial Pt/C catalyst. This excellent performance should be mainly due to effective N-doping and high porosity which can boost the mass transfer and charge transfer and provide a larger number of active sites for the ORR. The unique spherical morphologies with improved porosity as well as excellent stability and recyclability make these ANCSs among the most promising ORR electrocatalysts in practical applications

Imine-Linked Polymer-Derived Nitrogen-Doped Microporous Carbons with Excellent CO₂ Capture Properties

A series of nitrogen-doped microporous carbons (NCs) was successfully prepared by direct pyrolysis of high-surface-area microporous imine-linked polymer (ILP, 744 m²/g) which was formed using commercial starting materials based on the Schiff base condensation under catalyst-free conditions. These NCs have moderate specific surface areas of up to 366 m²/g, pore volumes of 0.43 cm³/g, narrow micropore size distributions, and a high density of nitrogen functional groups (5.58–8.74%). The resulting NCs are highly suitable for CO₂ capture adsorbents because of their microporous textural properties and large amount of Lewis basic sites. At 1 bar, NC-800 prepared by the pyrolysis of ILP at 800 °C showed the highest CO₂ uptakes of 1.95 and 2.65 mmol/g at 25 and 0 °C, respectively. The calculated adsorption capacity for CO₂ per m² (μmol of CO₂/m²) of NC-800 is 7.41 μmol of CO₂/m² at 1 bar and 25 °C, the highest ever reported for porous carbon adsorbents. The isosteric heats of CO₂ adsorption (<i>Q</i>_st) for these NCs are as high as 49 kJ/mol at low CO₂ surface coverage, and still ∼25 kJ/mol even at high CO₂ uptake (2.0 mmol/g), respectively. Furthermore, these NCs also exhibit high stability, excellent adsorption selectivity for CO₂ over N₂, and easy regeneration and reuse without any evident loss of CO₂ adsorption capacity

Auto-optimizing Hydrogen Evolution Catalytic Activity of ReS₂ through Intrinsic Charge Engineering

Optimizing active electronic states responding to catalysis is of paramount importance for developing high-activity catalysts because thermodynamics itself may not favor forming an optimal electronic state. Setting the monolayer transition metal dichalcogenide (TMD) ReS₂ as a model for the hydrogen evolution reaction (HER), we uncover that intrinsic charge engineering has an auto-optimizing effect on enhancing catalytic activity through regulating active electronic states. The experimental and theoretical results show that intrinsic charge compensation from S to Re–Re bonds could manipulate the active electronic states, allowing hydrogen to absorb the active sites neither strongly nor weakly. Two types of S sites exhibit the optimal hydrogen adsorption free energies (Δ<i>G</i>_H*) of 0.016 and 0.061 eV, which are the closest to zero corresponding to the highest HER activity. This auto-optimization via charge engineering is further demonstrated by higher turnover frequency per sulfur atom of 1–10 s^–1 and lower overpotential of −147 mV at 10 mA cm^–2 than those of other TMDs through multiscale activation and optimization. This work opens an avenue in designing extensive active catalysts through intrinsic charge engineering strategy

Subnanocyclic Molecule of 15-Crown‑5 Inhibiting Interfacial Water Decomposition and Stabilizing Zinc Anodes via Regulation of Zn²⁺ Solvation Shell

Aqueous zinc ion batteries exhibit a promising application prospect for next-generation energy storage devices. However, the decomposition of active H2O molecules on the Zn anode induces drastic dendrite formation, thereby impairing the performance for entire devices. To solve this challenge, we introduce subnanocyclic molecules of 15-Crown-5 as an additive into ZnSO4 electrolyte to stabilize the Zn anode. Owing to the binding property of crown ethers with alkali metal ions and the size-fit rule, the 15-Crown-5 additives enable effective regulation of the solvation structure of hydrated Zn2+ and reduce the efficient contact between Zn anode and active H2O, which are validated by the experimental analysis and theoretical calculations. Under the assistance of the 15-Crown-5 additive, the as-assembled Zn-based batteries deliver superior performance compared with ZnSO4 and 18-Crown-6contaning ZnSO4 electrolytes. This work shows a bright direction toward progress in aqueous batteries

Subnanocyclic Molecule of 15-Crown‑5 Inhibiting Interfacial Water Decomposition and Stabilizing Zinc Anodes via Regulation of Zn²⁺ Solvation Shell

Aqueous zinc ion batteries exhibit a promising application prospect for next-generation energy storage devices. However, the decomposition of active H2O molecules on the Zn anode induces drastic dendrite formation, thereby impairing the performance for entire devices. To solve this challenge, we introduce subnanocyclic molecules of 15-Crown-5 as an additive into ZnSO4 electrolyte to stabilize the Zn anode. Owing to the binding property of crown ethers with alkali metal ions and the size-fit rule, the 15-Crown-5 additives enable effective regulation of the solvation structure of hydrated Zn2+ and reduce the efficient contact between Zn anode and active H2O, which are validated by the experimental analysis and theoretical calculations. Under the assistance of the 15-Crown-5 additive, the as-assembled Zn-based batteries deliver superior performance compared with ZnSO4 and 18-Crown-6contaning ZnSO4 electrolytes. This work shows a bright direction toward progress in aqueous batteries

Mesoporous Single Atom-Cluster Fe–N/C Oxygen Evolution Electrocatalysts Synthesized with Bottlebrush Block Copolymer-Templated Rapid Thermal Annealing

Current electrocatalysts for oxygen evolution reaction (OER) are either expensive (such as IrO2, RuO2) or/and exhibit high overpotential as well as sluggish kinetics. This article reports mesoporous earth-abundant iron (Fe)–nitrogen (N) doped carbon electrocatalysts with iron clusters and closely surrounding Fe–N4 active sites. Unique to this work is that the mechanically stable mesoporous carbon-matrix structure (79 nm in pore size) with well-dispersed nitrogen-coordinated Fe single atom-cluster is synthesized via rapid thermal annealing (RTA) within only minutes using a self-assembled bottlebrush block copolymer (BBCP) melamine–formaldehyde resin composite template. The resulting porous structure and domain size can be tuned with the degree of polymerization of the BBCP backbone, which increases the electrochemically active surface area and improves electron transfer and mass transport for an effective OER process. The optimized electrocatalyst shows a required potential of 1.48 V (versus RHE) to obtain the current density of 10 mA/cm2 in 1 M KOH aqueous electrolyte and a small Tafel slope of 55 mV/decade at a given overpotential of 250 mV, which is significantly lower than recently reported earth-abundant electrocatalysts. Importantly, the Fe single-atom nitrogen coordination environment facilitates the surface reconstruction into a highly active oxyhydroxide under OER conditions, as revealed by X-ray photoelectron spectroscopy and in situ Raman spectroscopy, while the atomic clusters boost the single atoms reactive sites to prevent demetalation during the OER process. Density functional theory (DFT) calculations support that the iron nitrogen environment and reconstructed oxyhydroxides are electrocatalytically active sites as the kinetics barrier is largely reduced. This work has opened a new avenue for simple, rapid synthesis of inexpensive, earth-abundant, tailorable, mechanically stable, mesoporous carbon-coordinated single-atom electrocatalysts that can be used for renewable energy production

Additional file 1 of Induction of therapeutic immunity and cancer eradication through biofunctionalized liposome-like nanovesicles derived from irradiated-cancer cells

Supplementary Material