Ultralow RuO2 Doped NiS2 Heterojunction as a Multifunctional Electrocatalyst for Hydrogen Evolution linking to Biomass Organics Oxidation.

Hydrogen energy and biomass energy are green and sustainable forms that can solve the energy crisis all over the world. Electrocatalytic water splitting is a marvelous way to produce hydrogen and biomass platform molecules can be added into the electrolyte to reduce the overpotential and meanwhile are converted into some useful organics, but the key point is the design of electrocatalyst. Herein, ultralow noble metal Ru is doped into NiS2 to form RuO2@NiS2 heterojunction. Amongst them, the 0.06 RuO2@NiS2 has low overpotentials of 363 mV for OER and 71 mV for HER in 1 m KOH, which are superior to the RuO2 and Pt/C. Besides, the 0.06 RuO2@NiS2 shows a low overpotential of 173 mV in 1 m KOH+0.1 m glycerol, and the glycerol is oxidized to glyceraldehyde and formic acid via the high Faraday efficiency GlyOR process, and the splitting voltage is only 1.17 V. In addition, the 0.06 RuO2@NiS2 has a low overpotential of 206 mV in 1 m KOH+0.1 m glucose, and the glucose is converted to glucaric acid, lactic acid, and formic acid. This work has a "one stone three birds" effect for the production of hydrogen, low splitting voltage, and high-value-added biomass chemicals.

Modified Supporting Materials to Fabricate Form Stable Phase Change Material with High Thermal Energy Storage.

Thermal energy storage (TES) is vital to the absorption and release of plenty of external heat for various applications. For such storage, phase change material (PCM) has been considered as a sustainable energy material that can be integrated into a power generator. However, pure PCM has a leakage problem during the phase transition process, and we should fabricate a form stable PCM composite using some supporting materials. To prevent the leakage problem during the phase transition process, two different methods, microencapsulation and 3D porous infiltration, were used to fabricate PCM composites in this work. It was found that both microsphere and 3D porous aerogel supported PCM composites maintained their initial solid state without any leakage during the melting process. Compared with the microencapsulated PCM composite, the 3D porous aerogel supported PCM exhibited a relatively high weight fraction of working material due to its high porosity. In addition, the cross-linked graphene aerogel (GCA) could reduce volume shrinkage effectively during the infiltration process, and the GCA supported PCM composite kept a high latent heat (∆H) and form stability.

Combined C-H functionalization/O-H insertion reaction to form tertiary ß-alkoxy substituted ß-aminophosphonates catalyzed by [Cu(MeCN)4]PF6.

The copper-catalyzed C-H functionalization/O-H insertion reaction of α-diazophosphonates with alcohols has been developed with iodine as an additive. In order to understand this reaction, we present here a possible mechanism for the combined reaction. This process provides straightforward access to tertiary ß-alkoxy substituted ß-aminophosphonate derivatives with moderate to good yields.

Cellulose Nanocrystal Embedded Composite Foam and Its Carbonization for Energy Application.

In this study, we fabricated a cellulose nanocrystal (CNC)-embedded aerogel-like chitosan foam and carbonized the 3D foam for electrical energy harvesting. The nanocrystal-supported cellulose foam can demonstrate a high surface area and porosity, homogeneous size ranging from various microscales, and a high quality of absorbing external additives. In order to prepare CNC, microcrystalline cellulose (MCC) was chemically treated with sulfuric acid. The CNC incorporates into chitosan, enhancing mechanical properties, crystallization, and generation of the aerogel-like porous structure. The weight percentage of the CNC was 2 wt% in the chitosan composite. The CNC/chitosan foam is produced using the freeze-drying method, and the CNC-embedded CNC/chitosan foam has been carbonized. We found that the degree of crystallization of carbon structure increased, including the CNCs. Both CNC and chitosan are degradable materials when CNC includes chitosan, which can form a high surface area with some typical surface-related morphology. The electrical cyclic voltammetric result shows that the vertical composite specimen had superior electrochemical properties compared to the horizontal composite specimen. In addition, the BET measurement indicated that the CNC/chitosan foam possessed a high porosity, especially mesopores with layer structures. At the same time, the carbonized CNC led to a significant increase in the portion of micropore.

Nano-injection molding with resin mold inserts for prototyping of nanofluidic devices for single molecular detection.

While injection molding is becoming the fabrication modality of choice for high-scale production of microfluidic devices, especially those used for in vitro diagnostics, its translation into the growing area of nanofluidics (structures with at least one dimension <100 nm) has not been well established. Another prevailing issue with injection molding is the high startup costs and the relatively long time between device iterations making it in many cases impractical for device prototyping. We report, for the first time, functional nanofluidic devices with dimensions of critical structures below 30 nm fabricated by injection molding for the manipulation, identification, and detection of single molecules. UV-resin molds replicated from Si masters served as mold inserts, negating the need for generating Ni-mold inserts via electroplating. Using assembled devices with a cover plate via hybrid thermal fusion bonding, we demonstrated two functional thermoplastic nanofluidic devices. The first device consisted of dual in-plane nanopores placed at either end of a nanochannel and was used to detect and identify single ribonucleotide monophosphate molecules via resistive pulse sensing and obtain the effective mobility of the molecule through nanoscale electrophoresis to allow its identification. The second device demonstrated selective binding of a single RNA molecule to a solid phase bioreactor decorated with a processive exoribonuclease, XRN1. Our results provide a simple path towards the use of injection molding for device prototyping in the development stage of any nanofluidic or even microfluidic application, through which rapid scale-up is made possible by transitioning from prototyping to high throughput production using conventional Ni mold inserts.

Interface engineering Ni/Ni12P5@CNx Mott-Schottky heterojunction tailoring electrocatalytic pathways for zinc-air battery.

Due to the poor bifunctional electrocatalytic performances of electrocatalysts in zinc-air battery, herein, we first synthesized Ni/Ni12P5@CNx Mott-Schottky heterojunction to ameliorate the high-cost and instability of precious metals. We modulated the different contents of Ni and Ni12P5 in the Ni/Ni12P5@CNx Mott-Schottky heterojunction, and found that 0.6 Ni/Ni12P5@CNx has outstanding electrocatalytic performances, with half-wave potential of 0.83 V, and OER potential of 1.49 V at 10 mA cm-2. Also, the ΔE value is only 0.66 V. Moreover, 0.6 Ni/Ni12P5@CNx is assembled into ZAB, which has a high power density of 181 mW cm-2 and a high specific capacity of 710 mAh g-1. This indicates it has a good cycle stability. The density functional theory (DFT) calculations reveal that electrons spontaneously flow from Ni to Ni12P5 through the formed buffer layer in the Ni/Ni12P5@CNx Mott-Schottky heterojunction. The Schottky barrier formed modulates the electrocatalytic pathway to have good bifunctional electrocatalytic activity for ORR and OER.

Phase Change Material (PCM) Composite Supported by 3D Cross-Linked Porous Graphene Aerogel.

Integration of form-stable phase change material (PCM) composites with a pyro system can provide sufficient electrical energy during the light-on/off process. In this work, modified 3D porous graphene aerogel is utilized as a reliable supporting material to effectively reduce volume shrinkage during the infiltration process. Poly(vinylidene difluoride) (PVDF) is used for a transparent pyro film in the pyro system. The temperature fluctuation gives rise to a noise effect that restricts the generation of energy harvesting. The cross-linked graphene aerogel consisting of PCM composites can stabilize the temperature fluctuation in both melting and cooling processes. This shows that PCM composites can be applied to the pyro system under the change of the external environment. To evaluate the experimental results, a numerical simulation was conducted by using the finite element method (FEM).

Characterization of Phase Change Materials Fabricated with Cross-Linked Graphene Aerogels.

3D porous graphene aerogel exhibits a high surface area which can hold plenty of pure phase change material (PCM) into the internal space. In order to maintain the flexibility of PCM without volume shrinkage under the external force, cross-linked graphene aerogel was prepared by the cysteamine vapor method. The cross-linked graphene aerogel had a high stress-strain durability and chemical stability for infiltrating PCM to produce a form-stable PCM composite. The latent heat of PCM is one of the elements to estimate the capacity of PCM thermal energy storage (TES) during the phase transition process. The cross-linked graphene aerogel-supported PCM composite showed a great TES to be utilized in thermal-to-electrical energy harvesting. The cross-linked graphene aerogel also had an excellent mechanical property of preventing damage at a high temperature.

Analysis of Thermoelectric Energy Harvesting with Graphene Aerogel-Supported Form-Stable Phase Change Materials.

Graphene aerogel-supported phase change material (PCM) composites sustain the initial solid state without any leakage problem when they are melted. The high portion of pure PCM in the composite can absorb or release a relatively large amount of heat during heating and cooling. In this study, these form-stable PCM composites were used to construct a thermoelectric power generator for collecting electrical energy under the external temperature change. The Seebeck effect and the temperature difference between the two sides of the thermal device were applied for thermoelectric energy harvesting. Two different PCM composites were used to collect the thermoelectric energy harvesting due to the different phase transition field in the heating and cooling processes. The graphene nano-platelet (GNP) filler was embedded to increase the thermal conductivities of PCM composites. Maximum output current was investigated by utilizing these two PCM composites with different GNP filler ratios. The thermoelectric energy harvesting efficiencies during heating and cooling were 62.26% and 39.96%, respectively. In addition, a finite element method (FEM) numerical analysis was conducted to model the output profiles.