One-Step Synthesis of a Non-Precious-Metal Tris (Fe/N/F)-Doped Carbon Catalyst for Oxygen Reduction Reactions.

Advancements in inexpensive, efficient, and durable oxygen reduction catalysts is important for maintaining the sustainable development of fuel cells. Although doping carbon materials with transition metals or heteroatomic doping is inexpensive and enhances the electrocatalytic performance of the catalyst, because the charge distribution on its surface is adjusted, the development of a simple method for the synthesis of doped carbon materials remains challenging. Here, a non-precious-metal tris (Fe/N/F)-doped particulate porous carbon material (21P2-Fe1-850) was synthesized by employing a one-step process, using 2-methylimidazole, polytetrafluoroethylene, and FeCl3 as raw materials. The synthesized catalyst exhibited a good oxygen reduction reaction performance with a half-wave potential of 0.85 V in an alkaline medium (compared with 0.84 V of commercial Pt/C). Moreover, it had better stability and methanol resistance than Pt/C. This was mainly attributed to the effect of the tris (Fe/N/F)-doped carbon material on the morphology and chemical composition of the catalyst, thereby enhancing the catalyst's oxygen reduction reaction properties. This work provides a versatile method for the gentle and rapid synthesis of highly electronegative heteroatoms and transition metal co-doped carbon materials.

Facet-dependent CO2 reduction reactions on kesterite Cu2ZnSnS4 photo-electro-integrated electrodes.

Photoelectrochemical CO2 reduction by Cu2ZnSnS4 (CZTS) photocathodes is a potentially low-cost and high-efficiency CO2 conversion approach. However, the current CZTS-based photocathodes for the CO2 reduction reaction (CO2RR) are challenged by the active side reaction of the hydrogen evolution reaction (HER) and the incompatibility with efficient electrocatalysts. In this work, by means of density functional theory (DFT), we predict that a (220)-facet-suppressed kesterite CZTS could be an efficient photo-electro-integrated photocathode for formic acid production in the CO2RR. The results show that the competitive HER is mostly favored on the (220) facet. And the CO2RR for formic acid production on the (112) and (312) facets exhibits a thermodynamic energy barrier lower than 0.26 eV. Different from the d-band theory in metal electrocatalysts, it is found that the density of low energy unoccupied states in the S 3p orbital plays a key role in determining the CO2RR reaction path of the kesterite CZTS. Furthermore, two different trends of adsorption energy depending on the chemical characteristic of adsorbates are analyzed. Our study unveils the potential for selectively reducing CO2 into formic acid with kesterite CZTS and provides a possible route for manipulating the electrocatalytic properties of metal sulfide catalysts.

High-Performance Zinc-Ion Hybrid Supercapacitor from Guilin Sanhua Liquor Lees-Derived Carbon Materials.

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) have attracted considerable attention because they are inexpensive and safe. However, the inadequate energy densities, power densities, and cycling performance of current ZHSC energy-storage devices are impediments that need to be overcome to enable the further development and commercialization of this technology. To address these issues, in this study, we prepared carbon-based ZHSCs using a series of porous carbon materials derived from Sanhua liquor lees (SLPCs). Among them, the best performance was observed for SLPC-A13, which exhibited excellent properties and a high-surface-area structure (2667 m2 g-1) with abundant micropores. The Zn//SLPC-A13 device was assembled by using 2 mol L-1 ZnSO4, SLPC-A13, and Zn foil as the electrolyte, cathode, and anode, respectively. The Zn//SLPC-A13 device delivered an ultrahigh energy density of 137 Wh kg-1 at a power density of 462 W kg-1. Remarkably, Zn//SLPC-A13 retained 100% of its specific capacitance after 120,000 cycles of long-term charge/discharge testing, with 62% retained after 250,000 cycles. This outstanding performance is primarily attributed to the SLPC-A13 carbon material, which promotes the rapid adsorption and desorption of ions, and the charge-discharge process, which roughens the Zn anode in a manner that improves reversible Zn-ion plating/stripping efficiency. This study provides ideas for the preparation of ZHSC cathode materials.

High-performance atomic Co/N co-doped porous carbon catalysts derived from Co-doped metal-organic frameworks for oxygen reduction.

Improving the activity and durability of carbon-based catalysts is a key challenge for their application in fuel cells. Herein, we report a highly active and durable Co/N co-doped carbon (CoNC) catalyst prepared via pyrolysis of Co-doped zeolitic-imidazolate framework-8 (ZIF-8), which was synthesized by controlling the feeding sequence to enable Co to replace Zn in the metal-organic framework (MOF). The catalyst exhibited excellent oxygen reduction reaction (ORR) performance, while the half-wave potential decreased by only 8 mV after 5,000 accelerated stress test (AST) cycles in an acidic solution. Furthermore, the catalyst exhibited satisfactory cathodic catalytic performance when utilized in a hydrogen/oxygen single proton exchange membrane (PEM) fuel cell and a Zn-air battery, yielding maximum power densities of 530 and 164 mW cm-2, respectively. X-ray absorption spectroscopy (XAS) and high-angle annular dark field-scanning transmission electron microscopy (HAAD-STEM) analyses revealed that Co was present in the catalyst as single atoms coordinated with N to form Co-N moieties, which results in the high catalytic performance. These results show that the reported catalyst is a promising material for inclusion into future fuel cell designs.

N-Octadecane Encapsulated by Assembled BN/GO Aerogels for Highly Improved Thermal Conductivity and Energy Storage Capacity.

The rapid development of industry has emphasized the importance of phase change materials (PCMs) with a high latent-heat storage capacity and good thermal stability in promoting sustainable energy solutions. However, the inherent low thermal conductivity and poor thermal-cycling stability of PCMs limit their application. In this study, we constructed three-dimensional (3D) hybrid graphene aerogels (GBA) based on synergistic assembly and cross-linking between GO and modified hexagonal boron nitride (h-BN). Highly thermally conductive GBA was utilized as the supporting optimal matrix for encapsulating OD, and further implied that composite matrix n-octadecane (OD)/GBA composite PCMs were further prepared by encapsulating OD within the GBA structure. Due to the highly thermally conductive network of GBA, the latent heat of the composite PCMs improved to 208.3 J/g, with negligible changes after 100 thermal cycles. In addition, the thermal conductivity of the composite PCMs was significantly enhanced to 1.444 W/(m·k), increasing by 738% compared to OD. These results sufficiently confirmed that the novel GBA with a well-defined porous structure served as PCMs with excellent comprehensive performance offer great potential for thermal energy storage applications.

Annealing-Insensitive, Alcohol-Processed MoOx Hole Transport Layer for Universally Enabling High-Performance Conventional and Inverted Organic Solar Cells.

At present, most solution-processed molybdenum oxide (s-MoOx) hole transport layers (HTLs) are still mainly used in conventional organic solar cells (OSCs) but unsuitable for inverted OSCs. Herein, we demonstrate for the first time an annealing-insensitive, alcohol-processed MoOx HTL that can universally enable high-performance conventional and inverted OSCs. The s-MoOx HTL is spin-coated from the MoOx nanoparticle dispersion in alcohol, where the MoOx nanoparticles are synthesized by simple nonaqueous pyrolysis conversion of MoO2(acac)2. The MoOx nanoparticles possess uniform and very small sizes of less than 5 nm and can be well dispersed in alcohol, so the s-MoOx HTLs on ITO and active layer both show an overall uniform and smooth surface, suitable for conventional and inverted OSCs. In addition, the s-MoOx HTL possesses decent optical transmittance and appropriate work function. Utilizing the s-MoOx HTL annealed between room temperature and 110 °C and PM6:Y6 active layer, the conventional OSCs show an excellent power conversion efficiency (PCE) of 16.64-17.09% and the inverted OSCs also show an excellent PCE of 15.74-16.28%, which indicate that the s-MoOx HTL could be annealing-insensitive and universal for conventional and inverted OSCs. Moreover, conventional and inverted OSCs with the s-MoOx HTLs annealed at 80 °C both exhibit optimal PCEs of 17.09 and 16.28%, respectively, which are separately superior than that of the PEDOT:PSS-based conventional OSCs (16.94%) and the thermally evaporated MoO3 (e-MoO3)-based inverted OSCs (16.03%). Under light soaking and storage aging in air, the unencapsulated inverted OSCs based on the s-MoOx HTL show similarly excellent ambient stability compared to the e-MoOx-based devices. In addition, the s-MoOx HTL also shows a universal function in conventional and inverted OSCs with PBDB-T:ITIC and PM6:L8-BO active layers. Notably, the s-MoOx-based conventional and inverted OSCs with the PM6:L8-BO active layer exhibit very excellent PCEs of 18.21 and 17.12%, respectively, which are slightly higher than those of the corresponding PEDOT:PSS-based device (18.17%) and e-MoO3-based device (17.00%). The annealing-insensitive, alcohol-processed MoOx HTL may be very promising for flexible and large-scale processing conventional/inverted OSCs.

Cadmium Sulfide-Reinforced Double-Shell Microencapsulated Phase Change Materials for Advanced Thermal Energy Storage.

Phase change materials (PCMs) are widely used to improve energy utilization efficiency due to their high energy storage capacity. In this study, double-shell microencapsulated PCMs were constructed to resolve the liquid leakage issue and low thermal conductivity of organic PCMs, which also possess high thermal stability and multifunctionality. We used assembly to construct an inorganic-organic double shell for microencapsulate PCMs, which possessed the unprecedented synergetic properties of a cadmium sulfide (CdS) shell and melamine-formaldehyde polymeric shell. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirmed the well-designed double-shell structure of the microcapsules, and the CdS was successfully assembled as the second shell on the surface of the polymer shell. The differential scanning calorimeter (DSC) showed that the double-shell microcapsules had a high enthalpy of 114.58 J/g, which indicated almost no changes after experiencing 100 thermal cycles, indicating good thermal reliability. The microcapsules also showed good shape stability and antileakage performance, which displayed no shape change and leakage after heating at 60 °C for 30 min. In addition, the photothermal conversion efficiency of the double-shell microcapsules reached 91.3%. Thus, this study may promote the development of microencapsulated PCMs with multifunctionality, offering considerable application prospects in intelligent temperature management for smart textiles and wearable electronic devices in combination with their solar thermal energy conversion and storage performance.

Modified Circumcision Using the Disposable Circumcision Suture Device in Children: A Randomized Controlled Trial.

OBJECTIVE: To evaluate and compare the surgical outcomes and complications of the modified circumcision using disposable circumcision suture device (device group) and the conventional dorsal slit circumcision (conventional group) in children. METHODS: A total of 284 patients were randomized to either device group or conventional group. All patients were preoperatively assessed and evaluated at 4 weeks after surgery. The perioperative data and postoperative outcomes were compared between the 2 groups. RESULTS: No statistical differences were observed in the average age and indications between the 2 groups preoperatively (P > .05). Compared with the conventional group, patients in the device group were shorter mean operative time, less blood loss, lower intraoperative and postoperative pain score, faster incision healing time and a higher satisfaction rate of penile cosmetic appearance (P < .01). Similarly, the incidences of complication were significantly lower in the device group than in the conventional group (4.3% vs 12.3%, P < .05). CONCLUSIONS: The modified circumcision using disposable circumcision suture device is a simple, safe, faster, and effective procedure and may become the attractive alternative to the conventional technique for the children, with a relatively lower complication rate and better cosmetic results. With the improvement of disposable circumcision suture device, the modified circumcision using disposable circumcision suture device has the potential to be widely used in the world.

NMR and theoretical study on interactions between diperoxovanadate complex and pyrazole-like ligands.

To understand the effects of pyrazole substitution on reaction equilibrium, the interactions between a series of pyrazole-like ligands and [OV(O(2))(2)(D(2)O)](-)/[OV(O(2))(2)(HOD)](-) were explored by using multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, HSQC, and variable temperature NMR in 0.15 mol/L NaCl ionic medium mimicking physiological conditions. These results show that the relative reactivities among the pyrazole-like ligands are 3-methyl-1H-pyrazole approximately 4-methyl-1H-pyrazole approximately 1H-pyrazole>1-methyl-1H-pyrazole. As a result, the main factor which affects the reaction equilibrium is the steric effect instead of the electronic effect of the methyl group of these ligands. A pair of isomers has been formed resulting from the coordination of 3-methyl-1H-pyrazole and a vanadium complex, which is attributed to different types of coordination between the vanadium atom and the ligands. Thus, the competitive coordination leads to the formation of a series of six-coordinate peroxovanadate species [OV(O(2))(2)L](-) (L, pyrazole-like ligands). Moreover, the results of density functional calculations provided a reasonable explanation on the relative reactivity of the pyrazole-like ligands as well as the important role of solvation in these reactions.