Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr(3)C(2), CrN, VC(N), VN, TiC, TiC(N), TiN, and V(2)O(3) all showed excellent catalytic activity for the reduction of I(3)(-) to I(-) in the electrolyte. Further, VC embedded in mesoporous carbon (VC-MC) was prepared through in situ synthesis. The I(3)(-)/I(-) DSC based on the VC-MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T(2)/T(-). The T(2)/T(-) DSCs using TiC and VC-MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby encourage their fundamental research and commercial application.

Nitrogen (N)-doped carbon materials are considered as the most promising alternative to replace noble-metal catalysts for electrocatalytic dechlorination of 1,2-dichloroethane (DCE), which is a promising reaction for industrial production and environmental protection. Unfortunately, the vague cognition of the catalytic active sites limits its further development. Herein, a series of surface N-doped porous carbon materials with adjustable N dopants were synthesized to identify the active sites for electrocatalytic dechlorination of DCE. The as-prepared catalyst showed fascinating DCE electrocatalytic dechlorination activity and ethylene selectivity at −2.75 V (vs SCE) with a current density of 17.94 mA cm–2 geometry and ethylene Faradaic efficiency of 21%. The post hydrogen treatment and X-ray photoelectron spectroscopic analysis experimentally proved that the oxidized N acts as the active site for the dechlorination of DCE to CH2CH2, which was further theoretically confirmed by first-principles calculations. This work would open avenues for the development of N-doped carbon and the production of ethylene in an efficient and environmentally benign manner.

Tungsten dioxide imbedded in mesoporous carbon (WO 2 ÀMC) was obtained by in situ synthesis and then introduced into dyesensitized solar cells (DSCs) as a counter electrode (CE) catalyst. Catalytic activity for redox couple regeneration was improved significantly through combining high electrical conductivity and catalytic activity into one material, WO 2 ÀMC, in which WO 2 served as a catalyst and MC served as an electrical conductor. This has been proved by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The triiodide/iodide-based DSC using WO 2 ÀMC as CE showed a high power conversion efficiency (PCE) of 7.76%, which surpassed the performance of the DSC using traditional Pt CE (7.55%). In addition, the WO 2 ÀMC and WO 2 nanorods exhibited higher catalytic activity than Pt for the regeneration of a new organic redox couple, di-5-(1-methyltetrazole) disulfide/5-mercapto-1-methyltetrazole NÀtetramethylammonium salt (T 2 /T À ). The PCE of the T 2 /T Àbased DSCs using WO 2 ÀMC, WO 2 , and Pt were 5.22, 4.66, and 3.09%, respectively.

Polymer metallization is extensively used in a variety of micro- and nanosystem technologies. However, the deposited metal film exhibits poor adhesion to polymer substrates, which may cause difficulties in many applications. In this work, ultraviolet (UV)-ozone surface modification is for the first time put forward to enhance the adhesion between metal films and polymer substrates. The adhesion of sputtered Cu films on UV-ozone modified poly(methyl methacrylate) (PMMA) substrates is enhanced by a factor of 6, and that of Au films is improved by a factor of 10. Moreover, metal films on the modified PMMA substrates can withstand a long-time liquid immersion. To understand the mechanism for the adhesion enhancement, the surface modification is studied with contact angle measurements, attenuated total reflection Fourier-transform infrared spectrometry (ATR-FTIR) and atomic force microscopy (AFM). Detailed characterization results indicate that the significant adhesion enhancement is attributed to the increases of both the surface wettability by generating some polar functional groups and the roughness of the surface in nanoscale. To demonstrate this novel polymer metallization method, a 6-in. PMMA chip with arrays of three-electrode electrochemical microsensors is designed and fabricated, and the microsensor exhibits excellent reproducibility, uniformity, and long-term stability.

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BackgroundVHG fermentation is a promising process engineering strategy aiming at improving ethanol titer, and thus saving energy consumption for ethanol distillation and distillage treatment. However, sustained process oscillation was observed during continuous VHG ethanol fermentation, which significantly affected ethanol fermentation performance of the system.ResultsSustained process oscillation was investigated in continuous VHG ethanol fermentation, and stresses exerted on yeast cells by osmotic pressure from unfermented sugars and ethanol inhibition developed within the fermentation system were postulated to be major factors triggering this phenomenon. In this article, steady state was established for continuous ethanol fermentation with LG medium containing 120 g/L glucose, and then 160 g/L non-fermentable xylose was supplemented into the LG medium to simulate the osmotic stress on yeast cells under the VHG fermentation condition, but the fermentation process was still at steady state, indicating that the impact of osmotic stress on yeast cells was not the main reason for the process oscillation. However, when 30 g/L ethanol was supplemented into the LG medium to simulate the ethanol inhibition in yeast cells under the VHG fermentation condition, process oscillation was triggered, which was augmented with extended oscillation period and exaggerated oscillation amplitude as ethanol supplementation was increased to 50 g/L, but the process oscillation was gradually attenuated when the ethanol supplementations were stopped, and the steady state was restored. Furthermore, gas stripping was incorporated into the continuous VHG fermentation system to in situ remove ethanol produced by Saccharomyces cerevisiae, and the process oscillation was also attenuated, but restored after the gas stripping was interrupted.ConclusionsExperimental results indicated that ethanol inhibition rather than osmotic stress on yeast cells is one of the main factors triggering the process oscillation under the VHG fermentation condition, and in the meantime gas stripping was validated to be an effective strategy for attenuating the process oscillation.

Electrocatalytic dechlorination continually attracts attention in dealing with chlorinated volatile organic compounds (CVOCs) due to its mild reaction conditions, economical, and environmental friendliness. Unfortunately, the electrocatalysts were reported to suffer from low dechlorination reactivity and selectivity, as well as unclear active sites. Here, we developed a core−shell NiMn 2 O 4 (NiMn 2 O 4 −CS) via a facile solvothermal method as an efficient cathode catalyst for selective dechlorination of 1, 2-dichloroethane (1,2-DCA) into highly valuable ethylene. NiMn 2 O 4 −CS provided more active sites that could accelerate electron transfer efficiency and fix more intermediate species (*CH 2 CH 2 Cl). The as-prepared electrode showed significant current density (18.11 mA/cm 2 ) at a potential of −2.75 V (vs SCE) and an ethylene Faradaic efficiency of 41%. Transfer coefficient α points out a concerted mechanism of dechlorination. The first-principles calculations indicated that the Ni atoms in octahedral sites of NiMn 2 O 4 are the main active sites for 1,2-DCA dechlorination to ethylene. In addition, a remarkable charge transfer appeared between the intermediate of *CH 2 CH 2 Cl and the Ni oct sites of NiMn 2 O 4 . This work provides reasonable ideas for the design of dechlorination electrocatalysts and the friendly transformation of CVOCs.

A Pt/SiC nanocomposite with ~10 wt% Pt loading was used as a counter electrode (CE) in dye-sensitized solar cells (DSCs), it shows a high power conversion efficiency (PCE) of 7.07% (a DSC with a SiC CE has a PCE of 3.29%), reaching 98.5% of the level obtained using a Pt CE (7.18%). This work provides substantial support for developing low-cost Pt-loaded composite CEs for DSCs. Pt/SiC use is expected to reduce the dependence on the Pt in DSCs, while it can also be expected to be used in many chemical and electrochemical processes required to control the amount of Pt and prevent Pt nanoparticle aggregation.