A composite film of nickel sulfide/platinum/titanium foil (NiS/Pt/Ti) with low cost and high electrocatalytic activity was synthesized by the use of an in situ electropolymerization route and proposed as a counter electrode (CE) catalyst for flexible dye-sensitized solar cells (FDSSCs). The FDSSC with the NiS/Pt/Ti CE exhibited a comparable power conversion efficiency of 7.20% to the FDSSC with the platinum/titanium (Pt/Ti) CE showing 6.07%. The surface morphology of the NiS/Pt/Ti CE with one-dimensional (1D) structure is characterized by using the scanning electron microscopy (SEM). The NiS/Pt/Ti CE also displayed multiple electrochemical functions of excellent conductivity, great electrocatalytic ability for iodine/triiodine, and low charge transfer resistance of 2.61 ± 0.02 Ω cm2, which were characterized by using the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization plots. The photocurrent-photovoltage (J-V) character curves were further used to calculate the theoretical optical light performance parameters of the FDSSCs. It may be said that the NiS/Pt/Ti counter electrode is a promising catalytic material to replace the expensive platinum in FDSSCs.

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A highly efficient flexible dye-sensitized solar cell based on nickel sulfide/platinum/titanium counter electrode

Dye-sensitized solar cell (DSSC) offers an efficient and easily implemented technology for future energy supply. Compared to conventional silicon solar cells, it provides comparable power conversion efficiency (PCE) at low material and manufacturing costs. DSSC materials such as titanium oxide (TiO 2 ) are inexpensive, abundant and innocuous to the environment. Since DSSC materials are less prone to contamination and processable at ambient temperature, a roll-to-roll process could be utilized to print DSSCs on the mass production line. DSSCs perform better under lower light intensities, which makes them an excellent choice for indoor applications. Due to the advancement of molecular engineering, colored and transparent thin films have been introduced to enhance the aesthetic values. Up to now, such benefits have attracted considerable research interests and commercialization effort. Here, this review examines advanced techniques and research trends of this promising technology from the perspective of device modeling, state-of-art techniques, and novel device structures.

Review on dye-sensitized solar cells (DSSCs): Advanced techniques and research trends

Photocatalysis is a green technology which converts abundantly available photonic energy into useful chemical energy. With a rapid rise of flow photoreactors in the last decade, the design and development of novel semiconductor photocatalysts is happening at a blistering rate. Currently, developed synthetic approaches have allowed the design of diverse modified/unmodified semiconductor materials exhibiting enhanced performances in heterogeneous photocatalysis. In this review, we have classified the so far reported highly efficient modified/unmodified semiconductor photocatalysts into four different categories based on the elemental composition, band gap engineering and charge carrier migration mechanism in composite photocatalysts. The recent synthetic developments are reported for each novel semiconductor photocatalyst within the four different categories, namely: pure semiconductors, solid solutions, type-II heterojunction nanocomposites and Z-scheme. The motivation behind the synthetic upgrading of modified/unmodified (pure) semiconductor photocatalysts along with their particular photochemical applications and photoreactor systems have been thoroughly reviewed.

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Nanostructured materials for photocatalysis

Nanomaterials have emerged as an amazing class of materials that consists of a broad spectrum of examples with at least one dimension in the range of 1 to 100 nm. Exceptionally high surface areas can be achieved through the rational design of nanomaterials. Nanomaterials can be produced with outstanding magnetic, electrical, optical, mechanical, and catalytic properties that are substantially different from their bulk counterparts. The nanomaterial properties can be tuned as desired via precisely controlling the size, shape, synthesis conditions, and appropriate functionalization. This review discusses a brief history of nanomaterials and their use throughout history to trigger advances in nanotechnology development. In particular, we describe and define various terms relating to nanomaterials. Various nanomaterial synthesis methods, including top-down and bottom-up approaches, are discussed. The unique features of nanomaterials are highlighted throughout the review. This review describes advances in nanomaterials, specifically fullerenes, carbon nanotubes, graphene, carbon quantum dots, nanodiamonds, carbon nanohorns, nanoporous materials, core–shell nanoparticles, silicene, antimonene, MXenes, 2D MOF nanosheets, boron nitride nanosheets, layered double hydroxides, and metal-based nanomaterials. Finally, we conclude by discussing challenges and future perspectives relating to nanomaterials.

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Nanomaterials: a review of synthesis methods, properties, recent progress, and challenges

Due to their unique physicochemical properties, graphene-family nanomaterials (GFNs) are widely used in many fields, especially in biomedical applications Currently, many studies have investigated the biocompatibility and toxicity of GFNs in vivo and in intro Generally, GFNs may exert different degrees of toxicity in animals or cell models by following with different administration routes and penetrating through physiological barriers, subsequently being distributed in tissues or located in cells, eventually being excreted out of the bodies This review collects studies on the toxic effects of GFNs in several organs and cell models We also point out that various factors determine the toxicity of GFNs including the lateral size, surface structure, functionalization, charge, impurities, aggregations, and corona effect ect In addition, several typical mechanisms underlying GFN toxicity have been revealed, for instance, physical destruction, oxidative stress, DNA damage, inflammatory response, apoptosis, autophagy, and necrosis In these mechanisms, (toll-like receptors-) TLR-, transforming growth factor β- (TGF-β-) and tumor necrosis factor-alpha (TNF-α) dependent-pathways are involved in the signalling pathway network, and oxidative stress plays a crucial role in these pathways In this review, we summarize the available information on regulating factors and the mechanisms of GFNs toxicity, and propose some challenges and suggestions for further investigations of GFNs, with the aim of completing the toxicology mechanisms, and providing suggestions to improve the biological safety of GFNs and facilitate their wide application

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Toxicity of graphene-family nanoparticles: a general review of the origins and mechanisms

PEDOT:PSS and glucose assisted preparation of molybdenum disulfide/single-wall carbon nanotubes counter electrode and served in dye-sensitized solar cells

To improve the power conversion efficiency of dye-sensitized solar cells (DSSCs), a DSSC based on a transparent counter electrode (CE) and a piece of new aluminium foil as a reflector was devised. Owing to the simultaneous sunlight irradiation from the rear side, more dye molecules are excited and more carriers are generated, which greatly enhances the short-circuit current density and power conversion efficiency. In this work, a transparent electrode of nickel sulfide decorated with poly(3,4-ethylenedioxythiophene) (NiS/PEDOT) was prepared by a two-step electrochemical/chemical process. The NiS/PEDOT hybrid electrode utilizes the advances made in the use of NiS and PEDOT as the counter electrode for DSSCs. The incorporation of PEDOT conductive networks provides additional pathways for electron transport in the NiS/PEDOT hybrid electrode and thus facilitates increasing charge-transfer rate at the interface of the CE/electrolyte. The DSSC based on the NiS/PEDOT CE and a piece of new aluminium foil as a reflector achieved a higher power conversion efficiency of 8.47% compared to that of a DSSC irradiated from the front only (7.77%) under the irradiation of 100 mW cm−2 (AM 1.5G). The strategy of adding new aluminium foil as a reflector is of practical maneuverability and reference use than that of used two lights or mirrors, which provides a new and promising approach for enhancing the photovoltaic performances of solar cells in practice.

A strategy to enhance overall efficiency for dye-sensitized solar cells with a transparent electrode of nickel sulfide decorated with poly(3,4-ethylenedioxythiophene)

We report a new method as UV treatment of low-temperature processed to obtain tin oxide (SnO2) electron transport layers (ETLs). The results show that the high quality of ETLs can be produced by controlling the thickness of the film while it is treated by UV. The thickness is dependent on the concentration of SnO2. Moreover, the conductivity and transmittance of the layer are dependent on the quality of the film. A planar perovskite solar cell is prepared based on this UV-treated film. The temperatures involved in the preparation process are less than 90 °C. An optimal power conversion efficiency of 14.36% is obtained at the concentration of SnO2 of 20%. This method of UV treatment SnO2 film at low temperature is suitable for the low-cost commercialized application.

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UV Treatment of Low-Temperature Processed SnO 2 Electron Transport Layers for Planar Perovskite Solar Cells

Polypyrrole@platinum (PPy@Pt) composite film was successfully synthesized by using a one-step electrochemical method and served as counter electrode (CE) for efficient dye-sensitized solar cells (DSSCs). The PPy@Pt CE with one-dimensional structure exhibited excellent electrocatalytic activity and superior charge transfer resistance for I−/I3
 − electrolyte after being the cyclic voltammetry and electrochemical impedance spectroscopy tested. The photocurrent-photovoltage curves were further used to calculate the theoretical photoelectric performance parameters of the DSSCs. The DSSC based on the PPy@Pt CE achieved a remarkable power conversion efficiency of 7.35 %, higher about 19.9 % than that of conventional Pt CE (6.13 %). This strategy provides a new opportunity for fabricating low-cost and highly efficient DSSCs.

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Xingping Ma

Papers

A highly efficient flexible dye-sensitized solar cell based on nickel sulfide/platinum/titanium counter electrode

PEDOT:PSS and glucose assisted preparation of molybdenum disulfide/single-wall carbon nanotubes counter electrode and served in dye-sensitized solar cells

A strategy to enhance overall efficiency for dye-sensitized solar cells with a transparent electrode of nickel sulfide decorated with poly(3,4-ethylenedioxythiophene)

UV Treatment of Low-Temperature Processed SnO 2 Electron Transport Layers for Planar Perovskite Solar Cells

Efficient Dye-Sensitized Solar Cells Made from High Catalytic Ability of Polypyrrole@Platinum Counter Electrode