Publications

Environmentally friendly electrochemical hydrogen production needs the development of earth-abundant catalyst materials for the hydrogen evolution reaction with high activity and durability at neutral pH. In this work, the self-templating construction of a hollow amorphous CoMoS₄ nanotube array on carbon cloth (CoMoS₄ NTA/CC) is reported, using hydrothermal treatment of a Co(OH)F nanowire array on CC in (NH₄ )₂ MoS₄ solution. When used as a 3D electrode for hydrogen evolution electrocatalysis, the resulting CoMoS₄ NTA/CC demonstrates superior catalytic activity and strong long-term electrochemical durability in 1.0 M phosphate buffer solution (pH=7). It shows small onset overpotential of 21 mV and requires low overpotentials of 104 and 179 mV to drive geometrical current densities of 10 and 50 mA cm^-2 , respectively. Density functional theory calculations suggest that CoMoS₄ has a more favorable hydrogen adsorption free energy than Co(OH)F.

A series of core-shell-structured composite molecular sieves comprising zeolite single crystals (i.e., ZSM-5) as a core and ordered mesoporous silica as a shell were synthesized by means of a surfactant-directed sol-gel process in basic medium by using cetyltrimethylammonium bromide (CTAB) as a template and tetraethylorthosilicate (TEOS) as silica precursor. Through this coating method, uniform mesoporous silica shells closely grow around the anisotropic zeolite single crystals, the shell thickness of which can easily be tuned in the range of 15-100 nm by changing the ratio of TEOS/zeolite. The obtained composite molecular sieves have compact meso-/micropore junctions that form a hierarchical pore structure from ordered mesopore channels (2.4-3.0 nm in diameter) to zeolite micropores (≈0.51 nm). The short-time kinetic diffusion efficiency of benzene molecules within pristine ZSM-5 (≈7.88×10(-19) m(2) s(-1)) is almost retainable after covering with 75 nm-thick mesoporous silica shells (≈7.25×10(-19) m(2) s(-1)), which reflects the greatly opened junctions between closely connected mesopores (shell) and micropores (core). The core-shell composite shows greatly enhanced adsorption capacity (≈1.35 mmol g(-1)) for large molecules such as 1,3,5-triisopropylbenzene relative to that of pristine ZSM-5 (≈0.4 mmol g(-1)) owing to the mesoporous silica shells. When Al species are introduced during the coating process, the core-shell composite molecular sieves demonstrate a graded acidity distribution from weak acidity of mesopores (predominant Lewis acid sites) to accessible strong acidity of zeolite cores (Lewis and Brønsted acid sites). The probe catalytic cracking reaction of n-dodecane shows the superiority of the unique core-shell structure over pristine ZSM-5. Insight into the core-shell composite structure with hierarchical pore and graded acidity distribution show great potential for petroleum catalytic processes.

ABSTRACT Aloe vera (AV) gel has been widely used in various medical, cosmetic, and nutraceutical applications. However, AV rind, the tougher outer layer of AV leaves where the cell wall components exists, is currently treated as a fertilizer or waste. This study aimed to investigate the potential of the AV rind as a resource for the production of cellulose nanofibers. Since a detailed analysis of the AV rind has been lacking, chemical composition of rind was analyzed before processing it into nanofibers. The results showed that AV rind has a high proportion of α ‐cellulose (57.72% ± 2.18%). AV rind nanofibers (AVRNF) were prepared using chemi‐mechanical process. The morphological analyses showed that most of the isolated fibers were individual fibers under 20 nm. Crystallinity and degree of polymerization of the obtained AVRNF, and mechanical properties of the nanofibrous film were evaluated and compared with the wood nanofibers. Tensile strength of AVRNF film (102 MPa) was comparatively lower than the wood fibers (132 MPa), which was consistent with the lower crystallinity of AVRNF [crystallinity index (CI) = 0.66] as well as the lower degree of polymerization (DP = 396), compared with wood fibers (CI = 0.90, DP = 1297). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40592.

A NiMo hollow nanorod array is developed on Ti mesh <italic>via</italic> a template-assisted electrodeposition method as a bifunctional electrode for water splitting.

The growing environmental awareness toward the replacement of non-biodegradable materials with biodegradable materials has led many researchers for looking at many bio-based materials to suit various applications. This study objective to evaluate the morphology and properties of fibers extracted from Citrullus lanatus climber. The physical-chemical, thermal, mechanical, crystalline, morphological characteristics of Citrullus lanatus climber fibers were examined by Fourier transform-infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), single fiber tension test, X-ray diffraction (XRD), and scanning electron microscope (SEM). The test results showed cellulose content (53.7 wt. %), density (1227 kg/m3), crystallinity index (33.33%) which prove that Citrullus lanatus climber fibers can be used as reinforcement for light-weight medium load applications.

A general methodology to prepare MXene quantum dots (MxQDs) with yields over 20% by liquid-phase laser ablation of the MAX phase is reported. Mechanical and thermal shock by 532 nm laser pulses (7 ns fwhp, 50 mJ × pulse^-1 , 1 Hz pulse frequency) produces MAX etching and exfoliation to form MXene QDs, avoiding the use of HF. The process can be followed by absorption and emission spectroscopy and by dynamic laser scattering and it appears to be general, being applied to Ti₃ AlC₂ , Ti₂ AlC, Nb₂ AlC, and V₂ AlC MAX phases. Density functional theory calculations indicate that, depending on the surface terminal groups, the diminution of the MXene size to the nanometric scale makes it possible to control the band gap of the MXene. The photocatalytic activity of these MXene QDs for hydrogen evolution has been observed, reaching an H₂ production for the most efficient Ti₃ C₂ QDs as high as 2.02 mmol × g^-1 × h^-1 .

Chemically modified electrodes: The fast and effective immobilization of graphene on a Au electrode has been demonstrated by exploiting Au–S interactions between Au and a thiolated single-stranded DNA as well as π–π stacking interactions between graphene and DNA bases (see figure). The resultant modified electrode exhibits high sensitivity and selectivity in dopamine detection with a detection limit of 0.8 nM in the presence of ascorbic acid. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.