YPO4 nanoprisms and nanorods were synthesized by hydrothermal and co-precipitation processes. Au/YPO4 catalysts were obtained by a deposition-precipitation method. The as-prepared YPO4 and Au/YPO4 were characterized by N2 adsorption-desorption, XRD, TEM, XPS, ICP, UV-Vis DRS, and FT-IR. The XRD results revealed that YPO4 nanoprisms and nanorods were hexagonal phase. The TEM observations demonstrated that the gold nanoparticles with the size of <4 nm uniformly dispersed on the surface of the support. The XPS spectra revealed that gold was in the metallic state. The catalysis results demonstrated that Au/YPO4-rods performed higher catalytic activity than Au/YPO4-prisms for CO oxidation. 1.0% Au/YPO4-rods catalyst could achieve complete CO conversion at 20 °C. Au/YPO4-prisms exhibited higher sintering-resistant property than Au/YPO4-rods. After continuous operation for 10 h, Au/YPO4-rods showed better stability at low reaction temperature than Au/YPO4-prisms, and both of them showed good stability at the reaction temperature of 220 °C.

A highly efficient and stable Au–Cu/hydroxyapatite (HAP, Ca10(PO4)6(OH)2) catalyst was reported. HAP was prepared through a deposition–precipitation method. Au–Cu/HAP catalysts were obtained by a two-step impregnation approach. The samples were characterized by XRD, TEM, SEM, UV-Vis, ICP, XPS, H2-TPR, and O2-TPD. CO oxidation reaction was carried out to evaluate the catalytic performance of samples. TEM and UV-Vis results showed that the metallic particles supported on Au–Cu/HAP were smaller than those on Au/HAP, and they were highly dispersed on the HAP support. Patterns of XPS revealed that CuO nanoparticles were formed in the Cu/HAP catalyst, while CuO and Cu2O species coexisted in Au–Cu/HAP catalyst. Based on the O2-TPD data, the addition of copper to Au/HAP gave rise to more new O2 adsorption sites and bigger O2 adsorption capacity. The catalysis results indicated that the Au–Cu/HAP was capable of obtaining higher efficiency and stability compared with Au/HAP and Cu/HAP for CO oxidation. It was likely that the synergistic interaction between gold and CuOx phase created the most active sites on Au–Cu/HAP and was responsible for the enhanced activity and stability in comparison with Au/HAP and Cu/HAP.

In this paper, monoclinic phase BiPO4 nanorods were successfully prepared by a one-pot solvothermal route. Au/BiPO4 catalysts were obtained by a deposition–precipitation method. The samples were characterized by X-ray diffraction, transmission electron microscopy techniques, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. The TEM results exhibited a good dispersion of gold nanoparticles over the support. The XPS spectra revealed that gold was in the metallic state and bismuth was in the +3 oxidation state. The catalysis results demonstrated that BiPO4 nanorods could be a good support for gold catalysts. Among the prepared catalysts, the 1.5% Au/BiPO4 pretreated at 300 °C showed the best performance in CO oxidation and could achieve 100% CO oxidation at 40 °C. It retained 100% conversion after continuous operation for 10 h at 40 °C, and showed no deactivation after 50 h at a selected high reaction temperature of 180 °C. The possible mechanism of Au/BiPO4 catalysts in the CO oxidation was also proposed.

Lanthanum-modified TiO2 nanotube (NT) supported gold catalysts were prepared. The linear relationship between actual and nominal lanthanum concentrations was found. The possible formation mechanism of La-modified TiO2 NTs was suggested. The effects of calcination temperature, La concentration and gold loading on the catalytic activity for CO oxidation were investigated. Au/La2O3–TiO2-NTs (Au: 4.18%, La: 1.62%) calcined at 300 °C could completely convert CO at 30 °C. T100% of La-free catalyst was 60 °C. The catalytic activity of Au/TiO2-NTs could be improved by modification with lanthanum.

A new preparation method for Au/TiO2 nanotubes (NTs) by combing sol–gel with hydrothermal treatment technique was developed. The TiO2 NTs calcined at 300 °C were nearly uniform, and the gold particles were distributed homogeneously. The possible formation mechanism was suggested. The 5 % Au/TiO2 NTs calcined at 300 °C had the best catalytic activity for CO oxidation, and their conversion of CO remained at 100 % during 60 h on stream. This preparation method could improve the thermal stability of Au/TiO2 nanotube catalysts.

Hybrid nanomaterials combining the properties of different compositions, which may exhibit multiple functions, are of great significance from both scientific and practical perspectives. In this work, an efficient, green, and general strategy has been developed to fabricate Au(Pt)-functionalized α-Fe2O3 hybrid nanospindles. The morphology, structure, and composition of the hybrid nanostructures were characterized by means of XRD/TEM/XPS. Inspired by the unique functions of Au and α-Fe2O3, we have applied the Au/α-Fe2O3 hybrid nanospindles as a multifunctional nanomaterial for gas sensing and CO oxidation. The obtained results demonstrate that, after functionalization with Au nanoparticles, the hybrid nanospindles exhibit much higher activity for both applications compared to pristine α-Fe2O3, indicating a great potential for multifunctional applications.

B-doped TiO2 nanotubes (B/TiO2 NTs) were prepared by the combination of sol–gel process with hydrothermal treatment. The prepared catalysts were characterized by XRD, TEM and XPS. The photocatalytic activity of B/TiO2 NTs was evaluated through the photodegradation of aqueous methyl orange. The results demonstrated that the 1.5% B/TiO2 NTs calcined at 300 °C possessed the best photocatalytic activity. Compared with pure TiO2 nanotubes, the doping with B significantly enhanced the photocatalytic efficiency.

Cr-doped TiO2 nanotubes (Cr/TiO2 NTs) with high photocatalytic activity were prepared by the combination of sol–gel process with hydrothermal treatment. XRD, TEM and UV–vis DRS techniques were employed for microstructural characterization. TEM images show that Cr/TiO2 NTs are in good tubular structure and have diameter of about 10 nm. The Cr doping induces the shift of the absorption edge to the visible light range and the narrowing of the band gap. The photocatalytic experiment reveals that the photocatalytic performance of TiO2 NTs can be improved by the doping of chromium ions.

Ceria nanocrystals and CuO–CeO2 composite were prepared via alcohothermal technique using methanol as the solvent firstly and impregnation method. The catalytic activity of the samples was studied for low-temperature CO oxidation. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) showed that the prepared spherical CeO2 was cubic phase with good crystallinity and narrow particle size distribution. CuO was in non-crystal form in the CuO–CeO2 composite. Temperature-programmed reduction (TPR) and X-ray photoelectron spectra (XPS) analysis of the CuO–CeO2 composite indicated a two-step reduction and the possible presence of reduced copper species. The CuO–CeO2 composite exhibited obviously higher catalytic activity than CeO2 due to the synergistic effect.

Au@TiO2 core/shell nanoparticles were synthesized by a simple and efficient one-step method using tetrabutyl titanate as TiO2 precursor. The samples were characterized by TEM, XRD, UV–vis and XPS. The experiments demonstrated that the average particles size of Au was 10–15 nm, and the thickness of TiO2 shell was 1–3 nm. TiO2 shell induced a red-shift of the absorption peak of Au. This material exhibited catalytic activity for CO oxidation. This study offered an approach for CO oxidation by using Au@TiO2 model catalysts.