Shenlong Zhao

Three-Dimensional Graphene/Metal Oxide Nanoparticle Hybrids for High-Performance Capacitive Deionization of Saline Water

A novel and general method is proposed to construct three-dimensional graphene/metal oxide nanoparticle hybrids. For the first time, it is demonstrated that this graphene-based composite with open pore structures can be used as the high-performance capacitive deionization (CDI) electrode materials, which outperform currently reported materials. This work will offer a promising way to develop highly effective CDI electrode materials.

Carbonized Nanoscale Metal–Organic Frameworks as High Performance Electrocatalyst for Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is one of the key steps in clean and efficient energy conversion techniques such as in fuel cells and metal-air batteries; however, several disadvantages of current ORRs including the kinetically sluggish process and expensive catalysts hinder mass production of these devices. Herein, we develop carbonized nanoparticles, which are derived from monodisperse nanoscale metal organic frameworks (MIL-88B-NH3), as the high performance ORR catalysts. The onset potential and the half-wave potential for the ORR at these carbonized nanoparticles is up to 1.03 and 0.92 V (vs RHE) in 0.1 M KOH solution, respectively, which represents the best ORR activity of all the non-noble metal catalysts reported so far. Furthermore, when used as the cathode of the alkaline direct fuel cell, the power density obtained with the carbonized nanoparticles reaches 22.7 mW/cm2, 1.7 times higher than the commercial Pt/C catalysts.

Three dimensional N-doped graphene/PtRu nanoparticle hybrids as high performance anode for direct methanol fuel cells

A three-dimensional (3D) N-doped graphene aerogel with porous structures and uniformly distributed PtRu NPs (N-GA/PtRu) is constructed by a simple, rapid and eco-friendly method. The N-GA/PtRu exhibits an unprecedented performance towards the methanol electrochemical oxidation reaction. Notably, N-GA/PtRu can be directly used as the anode of direct methanol fuel cells by simple physical pressing without the need for any binders or additives.

Co3O4 Hexagonal Platelets with Controllable Facets Enabling Highly Efficient Visible-Light Photocatalytic Reduction of CO2

A heterogeneous catalyst made of well-defined Co3 O4 hexagonal platelets with varied exposed facets is coupled with [Ru(bpy)3 ]Cl2 photosensitizers to effectively and efficiently reduce CO2 under visible-light irradiation. Systematic investigation based on both experiment and theory discloses that the exposed {112} facets are crucial for activating CO2 molecules, giving rise to significant enhancement of photocatalytic CO2 reduction efficiency.

Three-dimensional graphene/Pt nanoparticle composites as freestanding anode for enhancing performance of microbial fuel cells.

A microbial fuel cell constructed with 3D freestanding graphene aerogel/platinum nanoparticles shows unprecedented performance. Microbial fuel cells (MFCs) are able to directly convert about 50 to 90% of energy from oxidation of organic matters in waste to electricity and have great potential application in broad fields such as wastewater treatment. Unfortunately, the power density of the MFCs at present is significantly lower than the theoretical value because of technical limitations including low bacteria loading capacity and difficult electron transfer between the bacteria and the electrode. We reported a three-dimensional (3D) graphene aerogel (GA) decorated with platinum nanoparticles (Pt NPs) as an efficient freestanding anode for MFCs. The 3D GA/Pt–based anode has a continuous 3D macroporous structure that is favorable for microorganism immobilization and efficient electrolyte transport. Moreover, GA scaffold is homogenously decorated with Pt NPs to further enhance extracellular charge transfer between the bacteria and the anode. The MFCs constructed with 3D GA/Pt–based anode generate a remarkable maximum power density of 1460 mW/m2, 5.3 times higher than that based on carbon cloth (273 mW/m2). It deserves to be stressed that 1460 mW/m2 obtained from the GA/Pt anode shows the superior performance among all the reported MFCs inoculated with Shewanella oneidensis MR-1. Moreover, as a demonstration of the real application, the MFC equipped with the freestanding GA/Pt anode has been successfully applied in driving timer for the first time, which opens the avenue toward the real application of the MFCs.

Efficient water oxidation under visible light by tuning surface defects on ceria nanorods

Fluorite CeO2 nanorods (NRs) with tunable surface defects are successfully prepared via hydrothermal synthesis followed by post-calcination under different atmospheres. Impressively, the CeO2 NRs obtained under mixed Ar and H-2 gas at 800 degrees C exhibit superior catalytic activity towards water oxidation under visible light (lambda >= 420 nm), which is 10 times higher than that of CeO2 NRs treated under air at 800 degrees C. Detailed characterization and theoretical analysis reveal that the rich surface defects including surface oxygen vacancies and Ce3+ ions are the origin of the enhanced water oxidation performance of the CeO2 NRs treated under the reduced atmosphere.

Cu2O clusters grown on TiO2 nanoplates as efficient photocatalysts for hydrogen generation

Conversion of solar energy into chemical energy in the form of so-called “solar fuels”, e.g., hydrogen, methane etc., is considered as one of the most promising methods to solve the future energy and environment challenges. Herein, ultrafine Cu2O clusters are in situ uniformly grown on the surface of TiO2 nanoplates (Cu2O/TiO2) via a one-pot hydrothermal method. The morphology and structure of Cu2O/TiO2 products are investigated by different characterization techniques. Furthermore, a detailed study on photocatalytic hydrogen generation demonstrates that the charge transfer of TiO2 with Cu2O loading is significantly accelerated, leading to high charge separation efficiency. Impressively, Cu2O/TiO2 exhibits superior catalytic activity towards water reduction, which is even higher than that of TiO2 loaded with noble metal Au nanoparticles. The strategy, facilitating charge transfer by construction of a heterojunction interface with cheap transition metal oxides, will offer the opportunity toward practical application of nanomaterials in energy conversion.

Multiple Au cores in CeO2 hollow spheres for the superior catalytic reduction of p-nitrophenol

In many catalytic systems the structure of the catalyst plays a crucial role in the reaction especially for catalytic reduction, organic pollutant oxidation and other organic transformations. Herein, we report a template-free approach to the synthesis of multiple Au cores in CeO2 hollow spheres (MACCHS). This material was fabricated by impregnating CeO2 hollow spheres with a HAuCl4 aqueous solution. NaBH4 was then used to reduce HAuCl4 to Au nanoparticles to form multiple Au cores in the CeO2 hollow spheres. We used MACCHS as a catalyst for p-nitrophenol reduction and achieved excellent activity. The catalyst showed enhanced stability toward p-nitrophenol reduction compared with bare Au nanoparticles and CeO2 hollow spheres. This simple method to achieve multi-core-in-shell hollow structures will likely have applications in various biological, medical and energy related fields.

Metallic Cobalt-Carbon Composite as Recyclable and Robust Magnetic Photocatalyst for Efficient CO2 Reduction

CO2 conversion into value-added chemical fuels driven by solar energy is an intriguing approach to address the current and future demand of energy supply. Currently, most reported surface-sensitized heterogeneous photocatalysts present poor activity and selectivity under visible light irradiation. Here, photosensitized porous metallic and magnetic 1200 CoC composites (PMMCoCC-1200) are coupled with a [Ru(bpy)3 ]Cl2 photosensitizer to efficiently reduce CO2 under visible-light irradiation in a selective and sustainable way. As a result, the CO production reaches a high yield of 1258.30 µL with selectivity of 64.21% in 6 h, superior to most reported heterogeneous photocatalysts. Systematic investigation demonstrates that the central metal cobalt is the active site for activating the adsorbed CO2 molecules and the surficial graphite carbon coating on cobalt metal is crucial for transferring the electrons from the triplet metal-to-ligand charge transfer of the photosensitizer Ru(bpy)32+ , which gives rise to significant enhancement for CO2 reduction efficiency. The fast electron injection from the excited Ru(bpy)32+ to PMMCoCC-1200 and the slow backward charge recombination result in a long-lived, charge-separated state for CO2 reduction. More impressively, the long-time stability and easy magnetic recycling ability of this metallic photocatalyst offer more benefits to the photocatalytic field.

Bread-derived 3D macroporous carbon foams as high performance free-standing anode in microbial fuel cells

Microbial fuel cells (MFCs) are a promising clean energy source to directly convert waste chemicals to available electric power. However, the practical application of MFCs needs the increased power density, enhanced energy conversion efficiency and reduced electrode material cost. In this study, three-dimensional (3D) macroporous N, P and S co-doped carbon foams (NPS-CFs) were prepared by direct pyrolysis of the commercial bread and employed as free-standing anodes in MFCs. As-obtained NPS-CFs have a large specific surface area (295.07 m2 g-1), high N, P and S doping level, and excellent electrical conductivity. A maximum areal power density of 3134 mW m-2 and current density of 7.56 A m-2 are generated by the MFCs equipped with as-obtained NPS-CF anodes, which is 2.57- and 2.63-fold that of the plain carbon cloth anodes (areal power density of 1218 mW m-2 and current density of 2.87 A m-2), respectively. Such improvement is explored to mainly originate from two respects: the good biocompatibility of NPS-CFs favors the bacterial adhesion and enrichment of electroactive Geobacter species on the electrode surface, while the high conductivity and improved bacteria-electrode interaction efficiently promote the extracellular electron transfer (EET) between the bacteria and the anode. This study provides a low-cost and sustainable way to fabricate high power MFCs for practical applications.