Excellent capacitive storage performance of N-doped porous carbon derived from the orientation-guidance coupled with in-situ activation methodology.

The orientation-guidance coupled with in-situ activation methodology is developed to synthesize the N-doped porous carbon (NPC) with well-developed porosity and high specific surface area, using coal pitch as a carbon precursor. The orientation-guidance and activation are dedicated to generating microporous and mesoporous channels, respectively. The in-situ N incorporation into the carbon skeleton is realized along with the formation of porous carbon (PC), ensuring the uniformity of N doping. As an electrode material of supercapacitor, benefiting from the robust hexagon-like building block decorated with micro-mesoporous channels and N doping, NPC electrode affords a significant improvement in capacitive energy-storage performance, achieving a specific capacitance of up to 333F g-1 at 1 A/g, which far exceeds those of PC and activated carbon. Notably, even under high mass loading of 10 mg cm-2, the NPC maintains a satisfactory capacitance of 258F g-1 at 1 A/g. When employed as the anode in Li-ion capacitor (LIC), apart from exhibiting enhanced anode behavior compared to graphite anode, NPC also delivers exceptional cyclability. Furthermore, density functional theory calculations have validated the enhanced electrical conductivity and Li storage ability contributed by N doping, providing a theoretical foundation for the observed improvements in electrochemical performance. A full LIC configured with NPC anode delivers extraordinary Ragone performance and outstanding cyclability. This work also proposes a feasible way to realize the oriented conversion of coal pitch into high-performance electrode materials for electrochemical energy-storage devices.

Uncovering the mechanisms of efficient upconversion in two-dimensional perovskites with anti-Stokes shift up to 220 meV.

Phonon-assisted photon upconversion holds great potential for numerous applications, e.g., optical refrigeration. However, traditional semiconductors face energy gain limitations due to thermal energy, typically achieving only ~25 milli-electron volts at room temperature. Here, we demonstrate that quasi-two-dimensional perovskites, with a soft hybrid organic-inorganic lattice, can efficiently upconvert photons with an anti-Stokes shift exceeding 200 milli-electron volts. By using microscopic transient absorption measurements and density functional theory calculations, we explicate that the giant energy gain stems from strong lattice fluctuation leading to a picosecond timescale transient band energy renormalization with a large energy variation of around ±180 milli-electron volts at room temperature. The motion of organic molecules drives the deformation of inorganic framework, providing energy and local states necessary for efficient upconversion within a time constant of around 1 ps. These results establish a deep understanding of perovskite-based photon upconversion and offer previously unknown insights into the development of various upconversion applications.

Highly Dispersed Pt Catalysts on Hierarchically Mesoporous Organosilica@Silica Nanoparticles with a Core-Shell Structure for Polycyclic Aromatic Hydrogenation.

Hydrogenation of naphthalene can effectively reduce the content of aromatics in oil and generate high-value products. A series of Pt-based aluminum-modified core-shell-structured hierarchically periodic mesoporous organosilica@mesoporous silica nanoparticles (Pt/Al-x-PMOs@MSNs) were successfully synthesized and tested for the hydrogenation properties, with preferable mass transfer of macromolecular reactants in the pores and increasing the total acidity of the catalysts. Moreover, the physicochemical properties of the core-shell-structured Pt-based catalysts were systematically analyzed using various characterization techniques. At 300 °C, the naphthalene conversion on the Pt/Al-10-PMOs@MSNs catalyst reached up to 100%, the selectivity of trans-decalin reached 83.9%, and the rate constants (k1, k2) and TOF were 13.2 × 10-6 mol·g-1·s-1, 1.7 × 10-7 mol·g-1·s-1, and 218.8 h-1, respectively. In the presence of sulfur, the naphthalene hydrogenation over the Pt/Al-10-PMOs@MSN catalyst first decreased to around 40% and then recovered to the original level, which originated from the synergistic effect of the texture and chemical properties over the Pt/Al-10-PMOs@MSNs with an excellent performance.

A general strategy for semiconductor quantum dot production.

Mass production of semiconductor quantum dots (QDs) from bulk materials is highly desired but far from being satisfactory. Herein, we report a general strategy to mechanically tailor semiconductor bulk materials into QDs. Semiconductor bulk materials are routinely available via simple chemical precipitation. From their bulk materials, a variety of semiconductor (e.g., lead sulfide (PbS), cadmium sulfide (CdS), copper sulfide (CuS), ferrous sulfide (FeS), and zinc sulfide (ZnS)) QDs are successfully produced in high yields (>15 wt%). This is achieved by a combination of silica-assisted ball-milling and sonication-assisted solvent treatment. The as-produced QDs show intrinsic characteristics and outstanding water solubility (up to 5 mg mL-1), facilitating their practical applications. The QD dispersions present remarkable photoluminescence (PL) with exciton-dependence and nanosecond (ns)-scale lifetimes. The QDs-poly(methyl methacrylate) (PMMA) hybrid thin films demonstrate exciting solid-state fluorescence and exceptional nonlinear saturation absorption (NSA). Absolute modulation depths of up to 58% and saturation intensities down to 0.40 MW cm-2 were obtained. Our strategy could be applied to any semiconductor bulk materials and therefore paves the way for the construction of the complete library of semiconductor QDs.

The Influence of Pore Structure and Acidity on the Hydrodesulfurization of Dibenzothiophene over NiMo-Supported Catalysts.

A series of mesoporous materials of SBA-16 were in situ incorporated into ZSM-5 crystallites via a two-step self-assemble method, and hydrodesulfurization (HDS) catalysts were prepared on the corresponding ZSM-5/SBA-16 (ZS) composites. The characterization results indicated that ZSM-5 nanoseeds were fabricated into the silica framework of the ZS composites, and the three-dimensional Im3m cubic structure of SBA-16 was retained simultaneously. In addition, the ZS series materials possessed open pores and large surfaces, which would facilitate the diffusion of reactants in the mesoporous channels. Moreover, the introduction of ZSM-5 seeds into composites could enhance the acidities of supports. As a result, the NiMo/ZS series catalysts exhibited high activities for DBT HDS processes. The NiMo/ZS-160 catalyst exhibited the highest catalytic efficiency (96.5%), which was apparently attributed to the synergistic contributions of the physicochemical properties of ZS supports and the dispersion states of active metals. Correspondingly, DBT HDS reactions over the NiMo/ZS series catalysts mainly proceeded via a hydrogenation desulfurization route that benefitted from the enhanced acidities especially the total Brønsted acid.