Yizhao Li

Solid-state synthesis of SnO2–graphene nanocomposite for photocatalysis and formaldehyde gas sensing

A facile solid-state synthetic route has been developed to prepare a tin oxide–graphene (SnO2–graphene) nanocomposite. Graphene decorated with tin oxide (SnO2) nanoparticles was synthesized by in situ solid-state chemical reaction at room temperature. The obtained SnO2–graphene nanocomposite has been investigated for applications as a photocatalyst to degrade organic contaminants in water and a chemical sensor to detect various vapours. The experiment results show that the SnO2–graphene nanocomposite exhibited improved performances for photocatalytic decomposition of Methyl Orange and Rhodamine B, and formaldehyde sensing comparable with the SnO2 nanoparticles. The enhancement of properties is proposed to be related to the large specific surface area of the nanocomposite and the good electronic characteristics of graphene.

A general strategy for synthesis of metal nanoparticles by a solid-state redox route under ambient conditions

A general strategy has been developed to synthesize metal nanoparticles by solid-state redox reaction under ambient conditions. A series of metallic nanoparticles, such as Ni, Fe, Sn, Co nanoparticles, and bimetallic NiCo nanoparticles were prepared by using inexpensive metal salts and sodium borohydride (NaBH4). The obtained Ni nanoparticles showed excellent catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol. The protocol creates a novel and facile route for the synthesis of metal nanoparticles.

Solvent-Free Chemical Approach to Synthesize Various Morphological Co3O4 for CO Oxidation

Co3O4 nanomaterials with diverse morphologies were usually synthesized in liquid phase accompanied by the template or surfactant under harsh conditions, which further restricted their practical application. Herein, we reported an extremely simple and practical solid-state chemical method to synthesize Co3O4-octahedrons, -plates, and -rods. Among these, the shape control of Co3O4-octahedrons and Co3O4-plates involve variation of the amount of reactant, and the formation of Co3O4-rods with {110} facet can be achieved by replacing the reactant. The formation of the Co3O4 nanomaterials with different morphologies originated from the different microenvironments of reaction and the structure of reactants. The catalytic activity of Co3O4 samples for CO oxidation was evaluated in normal feed gas. The as-prepared Co3O4-rods exposed {110} facet exhibited superior catalytic activity for CO oxidation, which can be attributed to more oxygen defects on Co3O4-rods surface. Additionally, Co3O4-rods exhibited excellent durablility (without pretreatment) in normal feed gas, even in the presence of moisture, comparable or better than that reported in the literature. The practical and environmental friendly solvent-free strategy provided a new promising route for large-scale preparation of (metal) oxide with remarkable CO oxidation performance for practical application.

Dahlia-shaped BiOClxI1−x structures prepared by a facile solid-state method: Evidence and mechanism of improved photocatalytic degradation of rhodamine B dye

A rapid and cheap solid-state chemical process was employed to synthesize BiOClxI1-x (x=1.0, 0.75, 0.5, 0.25, 0) solid solutions with dahlia-shaped hierarchitectures. The dahlia-shaped BiOClxI1-x hierarchitectures were effectively constructed by nanoplates with a thickness about 5-13nm. The band gap structure of the solid solutions can be modulated by adjusting the composition ratio of Cl and I, which has a significant effect on the photocatalytic activity of the solid solutions. The dahlia-shaped BiOClxI1-x (x=0.75) solid solution exhibits excellent adsorption and effective photocatalytic performances for rhodamine B (RhB) under visible light irradiation, which degraded more than 98% of RhB within 60min under the visible light irradiation, it is higher than the reported bismuth oxyhalides materials. The trapping experiments confirmed that O2- and h+ played the major role in the photocatalytic process and the possible photocatalytic reaction mechanism was illustrated.

Facile solid-state synthesis of Fe/FeOOH hierarchical nanostructures assembled from ultrathin nanosheets and their application in water treatment

Iron-based hierarchical nanostructures with enhanced properties have attracted intense interest as sorbents for water treatment. It is important to design a facile and scalable procedure for the preparation of absorbents with hierarchical structures. Here, a green solid-state method for the fabrication of Fe/FeOOH hierarchical nanostructures (Fe-HNs) is developed. The obtained samples with sizes in the range of 500–800 nm are three-dimensional (3D) hierarchical structures assembled from ultrathin nanosheets. A plausible “reduction–oxidation” mechanism is proposed for the formation process of the Fe-HNs. The as-prepared Fe-HNs are utilized as an adsorbent for the removal of Congo red and Cr(VI) ions from aqueous solution. The results show that the adsorbent exhibits high adsorption capacity, fast adsorption rate, and superior magnetic isolation. These Fe-HNs prepared by a facile solid-state method display very promising potential application in water treatment as an adsorbent.

V-modified Co3O4 nanorods with superior catalytic activity and thermostability for CO oxidation

It is well known that Co3O4 nanomaterials with high catalytic activity can be easily deactivated at high temperature, which will further inhibit their practical applications in CO oxidation catalysis. Herein, we report a facile solvent-free strategy to synthesize V-modified Co3O4 nanorods. The V-modified Co3O4 nanorods (without pretreatment) showed superior catalytic activity for CO oxidation in normal feed gas, and 100% CO conversion can be achieved at a low temperature of 60 °C. Additionally, the incorporation of V into Co3O4 nanorods remarkably enhanced the sintering resistance performance at high temperature. Compared with unmodified Co3O4 nanorods, V-modified Co3O4 nanorods exhibit outstanding thermostability in the catalysis due to the strong interaction between V and Co. This is promising for the development of practical catalysts for CO oxidation with excellent anti-inactivation performance.

Solvent-free Strategy of Photocarriers Accumulated Site and Separated Path for Porous Hollow Spindle-Shaped BiPO4

Porous, hollow‐structure, inorganic nanomaterials have sparked considerable interest in catalysis and energy conversion systems. However, inorganic nanomaterials with porous hollow structures are generally synthesized under harsh conditions or through complicated procedures, which impedes large‐scale applications. Herein, we describe a novel solid‐state chemical strategy without using templates and surfactants to construct hollow spindle‐shaped BiPO4 (BP). A porous hollow structure containing rich surface oxygen vacancies was achieved by the heat treatment of BP in air at 600 °C (BP‐Air‐600 °C). Benefiting from the synergistic effect, the hollow porous structure increased light‐harvesting efficiency by multiple reflection and the plentiful oxygen vacancies decreased recombination rate of electron‐hole pairs. BP‐Air‐600 °C displays an excellent apparent rate constant for the degradation of methylene blue, which is about 4.7 times higher than that of BP. This study presents a green approach to rational design of porous hollow structured nanomaterials which possess richer surface oxygen defects and excellent photocatalytic performance.