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The multifunctional and smart ultraviolet photodetectors are of great significance and necessity for applications in many fields, especially in health and environmental risk monitoring. Hence, a wire-shaped photoelectrochemical type ultraviolet photodetector based on photoanode of TiO2 nanotube arrays (TNAs) fabricated by electrochemical anodization is demonstrated in this work. The TNAs can provide direct pathways for carriers and large internal surface area. The assembled UV detector presented a high photocurrent density of 110 μA cm−2, a high ON/OFF ratio of 467, and a fast rise and decay response time of 13 and 19 ms for the optimal thickness of the photoanode of TNAs. Moreover, the detectors also exhibited visible-blind characteristics and an excellent linear response even under weak irradiation (20–100 μW cm−2). The results are beneficial to realizing omnidirectional and wearable optoelectronic devices. [ABSTRACT FROM AUTHOR]

One-dimensional nanowires can provide a direct electron transmission channel, as a result, the photogenerated carriers can be more easily and quickly transferred to the current collector. In a photoelectrochemical (PEC) ultraviolet (UV) detector, photoanode assemble using nanowires also possesses a large specific surface area to be beneficial for contacting between the electrolyte and photoanode. In this work, the SrTiO3 nanowires are fabricated by electrospinning and then assembled PEC UV detectors. Under UV illumination, the detector based on the SrTiO3 nanowires presents a superior detection performance with a response time of 8 ms. In particular, the device exhibits an efficient detection ability for weak UV light. Under the UV illumination intensity of 5 μW cm− 2, the current density Jsc reaches 11.3 nA cm− 2. The device also presents visible-blind, outstanding linear response and excellent repeatability under periodic UV irradiation. [ABSTRACT FROM AUTHOR]

In order to solve the 'ultraviolet (UV) filtering problem' caused by traditional sandwich-type structure in photoelectrochemical (PEC) UV detector, we design a special electrode based on stainless steel mesh, which integrates the light absorption layer and the electron collection electrode in a simple way. In combination with an UV-transparent quartz substrate, UV light can directly reach the active material. The improved detector shows good visible-blind, self-powered, and linear response characteristics. The serious recombination caused by metal electrode is suppressed by depositing a barrier layer. The optimized device exhibits a high photoresponse of 0.103 A W−1 at 296 nm, a short recovery time of 250 ms, and very sensitive switching ability. Furthermore, the response range of the detector is expanded from 300 to 400 nm to the full near-UV region. Our work provides an efficient strategy to solve the key problem of the PEC UV detector. [ABSTRACT FROM AUTHOR]

In order to develop more efficient biomass thermochemical conversion technology, a 60-kW three-staged biomass gasification system was constructed, and pinewood was used as material to investigate the effect of key influential factors on gasifier operation. Results show that the tar yield in pyrolysis stage was around 43,023 mg/Nm3, which was mainly consisted of primary tar compounds, such as acids, furans, and phenols. Sum of phenols compounds account for about 50.1% of total tar compounds. With the increase of excess air coefficient, the temperature of char-bed was improved, which benefited the reduction reactions in char bed. At ER = 0.35, the operation of the gasifier achieved an optimization value: gasification efficiency, carbon conversion rate, and tar yield were 76.77%, 81.91%, and 99 mg/Nm3 respectively. Subsequently, a 3D CFD (computational fluid dynamics) model of the throat section was built. Six kinds of air injection styles were designed and simulated. Results show that tangential air blow with reasonable angle (θ = 30° in this work) improves the flow field in the furnace and eliminate flow stagnation zone near the wall, which benefits the tar cracking in the throat section. [ABSTRACT FROM AUTHOR]

In this paper, we present an optimal control model of a stochastic production–inventory with deteriorating items, emission tax and pollution abatement investment. In our model, the emission tax is levied on the firm’s environmental obsolescence rate of technology rather than the total amount of the environmental externality. Our objective is to apply Hamilton–Jacobi–Bellman (HJB) equation to solve the stochastic production–inventory system with deteriorating items, emission tax and pollution abatement investment; and derive the optimal production rate and pollution abatement investment rate that maximise the objective function value. The results are discussed with some illustrative examples for different demand rate functions, and sensitivity analysis is conducted to study the effect of changing the parameters and coefficients on the objective function value. [ABSTRACT FROM PUBLISHER]

We have demonstrated a photoelectrochemical solar-blind ultraviolet (UV) detector based on SrTiO3 (STO) nanocrystalline film in this work. The assembled UV detector presents a high on/off ratio of about 6433 under periodic UV irradiation, a high photocurrent density of 220.6 μA cm−2, and a fast response time of 9 ms. By introducing a block layer (BL) on fluorine-doped tin oxide substrate, the response and decay times are shortened to 6 ms and 8 ms, respectively. The BL plays a crucial part in hindering the recombination of electrons from electrolyte carriers and avoiding short circuits. Due to its excellent light capture capability, the detector based on SrTiO3 nanocrystalline exhibits high sensitivity to weak UV light (5 μW cm−2). Moreover, the detector also exhibits visible-blind characteristics and a good linear response. [ABSTRACT FROM AUTHOR]