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The present research aims to explore, by large-eddy simulation (LES), the potentiality and mechanism of multiple surface dielectric barrier discharge (multi-SDBD) plasma actuators to manipulate mean and fluctuating wind loads on a low-rise building. Three actuator configurations are located on the roof to induce directional wall jets in different directions. The effects of these configurations on flow structure and wind loads are studied in absence and presence of approaching flow. Results show that all subgrid-scale models can obtain accurate roof pressure, and for the diffusion and convection terms, the bounded central differencing scheme can provide more accurate predictions for the roof pressure. The control impact of active actuators gradually weakens with the increase of the approaching flow velocity. The direction of the wall jet can determine the position of the limited roof region with the reduced mean pressure coefficient. The multi-SDBD actuators continue to absorb the upstream flow and blow this flow downstream, meaning the wall jet exerts strong pressure on the local roof area at the end of the jet, which results in a significant reduction of the mean pressure coefficient. Furthermore, the counter-rotating vortices caused by the wall jet restrain the size and strength of the vortex shedding, thereby achieving the purpose of reducing the fluctuating pressure coefficient. Further analysis of the instantaneous vorticity fields indicates that the intensity and size of streamwise shedding vortices can be restrained by small-scale spanwise vortices induced by the plasma actuators. Under the action of the wall jet blowing from the trailing edge to the leading edge, the fluctuating lift and drag coefficients can be reduced by over 15% and the fluctuating pressure coefficient can be reduced by about 20% from the no actuation situation. [ABSTRACT FROM AUTHOR]

A novel hierarchically structured WO3–CNT@TiO2NS composite was prepared by the combination of solvothermal and liquid-phase chemistry deposition techniques. The obtained composite has a highly rough and porous structure with WO3 nanoparticles distributed uniformly on the surface. The photocatalytic performance was tested by photocatalytic degradation of methylene blue. It is indicated that the WO3–CNT@TiO2NS composite shows more remarkable improvement of the photocatalytic performance than that of the CNT@TiO2NS. In particular, the presence of 15 wt% WO3 enables reaching the highest photocatalytic activity, which is 4 times that of CNT@TiO2NS. The enhanced photocatalytic properties are mainly attributed to the more efficient photogenerated carrier separation, enhanced light absorption as well as the higher adsorption ability. It is suggested that WO3 deposition is a promising way to enhance the photocatalytic activity of a TiO2-based photocatalyst. [ABSTRACT FROM AUTHOR]

Exploration of high-performance photoanodes is considered as an essential challenge in photoelectrochemical (PEC) water splitting due to the complex four-electron reaction in water oxidation. Herein, the nano-structured WO 3 -Se heterojunction decorated by organic Nafion layer is designed. The optimized WO 3 -Se200-0.05Nafion photoanode shows a remarkable photocurrent of 1.40 mA cm -2 at 1.23 V versus reversible hydrogen electrode, which is 2.5-fold higher than that of pure WO 3 nanosheets (WO 3 NS) photoelectrode. Remarkably, the photocurrent increments of WO 3 -Se200-0.05Nafion is larger than the increment sum of WO 3 -Se200 and WO 3 -0.05Nafion, which affirming the synergistic effect of Se nanospheres and Nafion layer. The improved PEC performances are attributed to the quick charge separation and transfer, the increased electric conductivity, and the excellent kinetics of oxygen evolution, which is derived from the strong interaction among WO 3 , Se and Nafion. Meanwhile, the better visible-light harvesting from Se nanospheres as photosensitizer and the induction of transparent Nafion as a passivation layer can explain this synergy. It hopes this heterostructure design with organic Nafion decoration can inspire to exploit outstanding performance photoanodes for PEC water splitting., (© 2022 IOP Publishing Ltd.)

Transforming glyoxal to value-added glyoxylic acid (GA) is highly desirable but challenging due to the uncontrollable over-oxidation. In this work, we report on a first demonstration of semi-oxidation of glyoxal with high selectivity (86.5%) and activity on WO 3 nanoplate photoanode through the photoelectrochemical strategy. The optimization of reactivity was achieved via crystal facet regulation, showing a satisfactory GA production rate of 308.4 mmol m -2 h -2 , 84.0% faradaic efficiency, and 4.3% total solar-to-glyoxylic acid efficiency on WO 3 with enriched {200} facets at 1.6 V versus RHE. WO 3 with a high {200} facet ratio exhibits more efficient electron-hole transfer kinetics, resulting in the facilitated formation of hydroxyl radicals ( • OH) and glyoxal radicals. Meanwhile, the theoretical calculation results indicate that the high selectivity and activity come from the strong adsorption ability for glyoxal and the low reaction energy for glyoxal radical generation on the (200) facets of WO 3 . Moreover, the high energy demand toward oxalic acid production on WO 3 leads to the exciting semi-oxidation process.

Highly efficient and inexpensive electrocatalysts for oxygen evolution reaction (OER) are extensively studied for water splitting. Herein, a unique bimetallic nanocomposite CoNi(OH) 2 @NiCo 2 S 4 nanosheet arrays derived from metal-organic-frameworks (MOFs, CoNi-ZIF) is simply fabricated on Ni foam, endowing large specific surface area and outstanding electrical conductivity. Compared with their single-metallic counterparts, the bimetallic composite displays dramatically low overpotential and small Tafel slope as well as outstanding catalytic stability. The overpoptential at 20 mA cm -2 for CoNi(OH) 2 @NiCo 2 S 4 is only 230 mV in comparison with Ni(OH) 2 @Ni 3 S 2 (266 mV), Co(OH) 2 @Co 3 S 4 (294 mV) and RuO 2 ( η  = 302 mV). First-principle calculations based on density functional theory (DFT) are carried out and reveal that the introduction of Ni in Co(OH) 2 helps lowered the energy difference of Δ G OOH* -Δ G O* , and thereby boosting the OER reactivity. This study provides an effective approach for the rational construction of low-cost metal hybrids., (© 2022 IOP Publishing Ltd.)