Xu Zong

Enhancement of photocatalytic H2 evolution on CdS by loading MoS2 as Cocatalyst under visible light irradiation.

This communication presents our recent results that the activity of photocatalytic H2 production can be significantly enhanced when a small amount of MoS2 is loaded on CdS as cocatalyst. The MoS2/CdS catalysts show high rate of H2 evolution from photocatalytic re-forming of lactic acid under visible light irradiation. The rate of H2 evolution on CdS is increased by up to 36 times when loaded with only 0.2 wt % of MoS2, and the activity of MoS2/CdS is even higher than those of the CdS photocatalysts loaded with different noble metals, such as Pt, Ru, Rh, Pd, and Au. The junction formed between MoS2 and CdS and the excellent H2 activation property of MoS2 are supposed to be responsible for the enhanced photocatalytic activity of MoS2/CdS.

Crystal Facet Dependence of Water Oxidation on BiVO4 Sheets under Visible Light Irradiation

Monoclinic BiVO(4) crystals with preferentially exposed (040) facets were hydrothermally synthesized by using a trace amount of TiCl(3) as the directing agent; this function was confirmed by X-ray diffraction patterns (XRD) and high-resolution transmission electron microscopy (HRTEM). The effects of the directing agent TiCl(3) and the pH values applied during synthesis have been studied, and the optimized BiVO(4) sample with highly exposed (040) facet could be obtained by using 1.2 at.% of TiCl(3) as the directing agent at a pH value of 2. Some complementary techniques were also applied to exclude the effects of the structural and physical property changes, such as surface area and hydrophilicity. The photocatalytic activity of oxygen evolution on BiVO(4) is found to be proportionally correlated with the exposed surfaces of the (040) facet. It is assumed that the active sites with a BiV(4) structure on the exposed (040) facet is assigned to be responsible for the high activity of O(2) evolution.

Visible light driven H2 production in molecular systems employing colloidal MoS2 nanoparticles as catalyst

Colloidal MoS(2) nanoparticles with diameters of less than 10 nm were prepared with a simple solvothermal method and demonstrated high efficiency in catalyzing H(2) evolution in Ru(bpy)(3)(2+)-based molecular systems under visible light.

Cubic CeO2 nanoparticles as mirror-like scattering layers for efficient light harvesting in dye-sensitized solar cells

A new type of bilayered photoanodes with cubic CeO(2) nanoparticles as mirror-like scattering thin layers was prepared via a screen-printing technique for dye-sensitized solar cells (DSSCs). The light harvesting efficiency was significantly enhanced due to the mirror-like light scattering effect, resulting in noticeable ∼17.8% improvement of light-to-electric conversion efficiency.

Photocatalytic H2 production on Pt/TiO2–SO42− with tuned surface-phase structures: enhancing activity and reducing CO formation

Photocatalytic reforming of biomass is a promising way to produce hydrogen using renewable energy. Photocatalytic reforming of methanol on Pt/TiO2–SO42− as a model reaction of biomass reforming was investigated. Sulfated TiO2 (TiO2–SO42−) with a tunable surface phase was prepared by calcining commercially available titanium dioxide TiO2 (Degussa P25) with deposited sodium sulfate Na2SO4 as a modifier. Compared with P25, the as-prepared TiO2–SO42− with Pt co-catalyst shows an increase up to 6-fold in the activity for H2 production via photocatalytic reforming of methanol, and the CO (undesired product) concentration in the produced H2 is decreased by about two orders of magnitude. XRD patterns and UV Raman spectra clearly indicate that TiO2 depositing with Na2SO4 can significantly retard the phase transformation from anatase to rutile during calcination at elevated temperatures. It is proposed that both the phase composition and the high crystallinity of TiO2 contribute to the high H2 evolution activity. IR spectra of pyridine adsorption and the NH3-TPD profile show that the surface acid sites of the photocatalyst are greatly reduced after calcination at high temperatures. It is proposed that the decrease in the acidity of the samples might be responsible for the low CO selectivity.

Photocatalytic water oxidation on F, N co-doped TiO2 with dominant exposed {001} facets under visible light

Visible-light-responsive anatase TiO(2) platelets with dominant {001} facets were prepared via a facile nitridation reaction from a TiOF(2) precursor. The in situ co-doping of N and F in the anatase TiO(2) nanoparticles leads to drastically enhanced absorption and excellent water oxidation performance in the visible light region.

Scalable Low‐Cost SnS2 Nanosheets as Counter Electrode Building Blocks for Dye‐Sensitized Solar Cells

A new type of semitransparent SnS2 nanosheet (NS) films were synthesized using a simple and environmentally friendly solution-processed approach, which were subsequently used as a counter electrode (CE) alternative to the noble metal Pt for triiodide reduction in dye-sensitized solar cells (DSSCs). The resultant SnS2 -based CE with a thickness of about 300 nm exhibited excellent electrochemical catalytic activity for catalyzing the reduction of triiodide and demonstrated comparable power conversion efficiency of 7.64 % with that of expensive Pt-based CE in DSSCs (7.71 %). When functionalized with a small amount of carbon nanoparticles, the SnS2 NS-based CE showed even better performance of 8.06 % than Pt under the same conditions. Considering the facile fabrication method, optical transparency, low cost, and remarkable catalytic property, this study on SnS2 NSs may shed light on the large-scale production of electrocatalytic electrode materials for low-cost photovoltaic devices.

Nitrogen doping in ion-exchangeable layered tantalate towards visible-light induced water oxidation

An ion-exchangeable layered photocatalyst CsCa(2)Ta(3)O(10) was doped with nitrogen. The as-prepared photocatalyst (N-doped CsCa(2)Ta(3)O(10)) is stable and demonstrates high performance for catalyzing water oxidation under visible light irradiation.

A new type of carbon nitride-based polymer composite for enhanced photocatalytic hydrogen production

A new type of graphitic C3N4-based composite photocatalysts was designed and prepared by co-loading PEDOT as a hole transport pathway and Pt as an electron trap on C3N4. The as-prepared C3N4-PEDOT-Pt composites showed drastically enhanced activity for visible light-driven photocatalytic H2 production compared to those of C3N4-PEDOT and C3N4-Pt, possibly due to the spatial separation of the reduction and oxidation reaction sites.

Hydrothermal Synthesis of a Crystalline Rutile TiO2 Nanorod Based Network for Efficient Dye‐Sensitized Solar Cells

One-dimensional (1D) TiO2 nanostructures are desirable as photoanodes in dye-sensitized solar cells (DSSCs) due to their superior electron-transport capability. However, making use of the DSSC performance of 1D rutile TiO2 photoanodes remains challenging, mainly due to the small surface area and consequently low dye loading. Herein, a new type of photoanode with a three-dimensional (3D) rutile-nanorod-based network structure directly grown on fluorine-doped tin oxide (FTO) substrates was developed by using a facile two-step hydrothermal process. The resultant photoanode possesses oriented rutile nanorod arrays for fast electron transport as the bottom layer and radially packed rutile head-caps with an improved large surface area for efficient dye adsorption. The diffuse reflectance spectra showed that with the radially packed top layer, the light-harvesting efficiency was increased due to an enhanced light-scattering effect. A combination of electrochemical impedance spectroscopy (EIS), dark current, and open-circuit voltage decay (OCVD) analyses confirmed that the electron-recombiantion rate was reduced on formation of the nanorod-based 3D network for fast electron transport. As a resut, a light-to-electricity conversion efficiency of 6.31% was achieved with this photoanode in DSSCs, which is comparable to the best DSSC efficiencies that have been reported to date for 1D rutile TiO2 .