Lumin Zhu

Icephobic/anti-icing potential of superhydrophobic Ti6Al4V surfaces with hierarchical textures

The main purpose of this paper was to investigate the icephobic potential of hierarchical superhydrophobic surfaces, which were prepared by modifying micro-nanostructures (constructed by the combination of sand blasting and hydrothermal treatment) on the surfaces of Ti6Al4V alloy with fluoroalkylsilane (FAS-17). We previously reported that this hierarchical superhydrophobic surface displayed excellent non-wettability with apparent contact angle of 161° and sliding angle of 3°. Thus, the present study focused on the systematic characterizations and analyses of the icephobic potential of the superhydrophobic surfaces around three parameters, including icing-delay time, ice adhesion strength, and contact time of an impacting droplet on cold superhydrophobic surfaces. The results indicated that the icing-delay time of a droplet on the superhydrophobic surface was many times longer than that of a droplet on the smooth Ti6Al4V substrate, and the ice adhesion strength on superhydrophobic surface was greatly reduced, which was attributed to the Cassie wetting state of a droplet on the surface. Additionally, the dynamic droplet impact and rebound assay demonstrated that water droplets always bounced off of the superhydrophobic surfaces before freezing under subzero conditions.

In situ synthesis of two-dimensional leaf-like Cu2ZnSnS4 plate arrays as a Pt-free counter electrode for efficient dye-sensitized solar cells

Kesterite-structure Cu2ZnSnS4 (CZTS) has been proved to be a high-performance Pt-free counter electrode (CE) material for dye-sensitized solar cells (DSSCs). Herein, a green but powerful two-step method based on solvothermal treatment was proposed to synthesize semi-transparent two-dimensional (2D) leaf-like CZTS plate arrays (PLAr) in situ on a FTO glass substrate, without any post-treatments, such as annealing, toxic sulfurization, or coating with other ancillary materials. The growth mechanism of the 2D leaf-like CZTS PLAr based on solvothermal treatment was illustrated. A power conversion efficiency (PCE) of 7.09% was obtained by utilizing leaf-like CZTS PLAr as the CE. Surprisingly, the PCE increased to 8.67% assisted by a mirror reflection. The excellent performance of DSSCs could be attributed to the high catalytic surface area, fast photo-generated electron transport at the counter electrode/redox electrolyte interface, remarkable electrocatalytic activity for I3− reduction, low charge transfer resistance toward the reduction of I3− ions, and high diffusion coefficient of the I3−. This work provides a green and feasible approach to construct high-quality metal sulfide nanoarrays on arbitrary conductive substrates under mild conditions (i.e. low temperature, no annealing, green, speediness) and promotes the development of Pt-free sulfide materials for sustainable photovoltaic applications.

Facile synthesis of single crystalline sub-micron Cu2ZnSnS4 (CZTS) powders using solvothermal treatment

Single crystalline sub-micron Cu2ZnSnS4 (CZTS) powders were successfully synthesized by a facile solvothermal method, using L-cysteine as sulfur precursor. It was confirmed that pure kesterite structured CZTS powders were synthesized at 400 °C after 5 h, with the irregular polygonal particle size being 500 nm to 1 μm. Interestingly, single crystalline CZTS particles were also obtained by simple solvothermal treatment without post annealing. The H2S released from L-cysteine had an impact on the growth of CZTS particles at high temperature. Further, the as-synthesized CZTS powders were used as counter electrode for dye-sensitized solar cells (DSSCs) and it is indicated that the CZTS counter electrode based DSSCs show a conversion efficiency of 4.243%.

Local structure, nucleation sites and crystallization behavior and their effects on magnetic properties of Fe 81 Si x B 10 P 8−x Cu 1 ( x = 0~8)

In this work, an attempt has been made to reveal critical factors dominating the crystallization and soft magnetic properties of Fe81SixB10P8−xCu1 (x = 0, 2, 4, 6 and 8) alloys. Both melt spun and annealed alloys are characterized by differential scanning calorimetry, X-ray diffractometry, Mössbauer spectroscopy, transmission electron microscopy, positron annihilation lifetime spectroscopy and magnetometry. The changes in magnetic interaction between Fe atoms and chemical homogeneity can well explain the variation of magnetic properties of Fe81SixB10P8−xCu1 amorphous alloys. The density of nucleation sites in the amorphous precursors decreases in the substitution of P by Si. Meanwhile, the precipitated nanograins gradually coarsen, but the inhibiting effect of P on grain growth diminishes causing the increase of the crystallinity. Moreover, various site occupancies of Si are observed in the nanocrystallites and the Si occupancy in bcc Fe decreases the average magnetic moment of nanograins. Without sacrificing amorphous forming ability, we can obtain FeSiBPCu nanocrystalline alloy with excellent soft magnetic properties by optimizing the content of Si and P in the amorphous precursors.