Catalytic polymeric electrodes for direct borohydride fuel cells

Abstract not availableBita Bayatsarmadi, Alice Peters, Pejman Talem

Soft-templating synthesis of N-Doped mesoporous carbon nanospheres for enhanced oxygen reduction reaction

The development of ordered mesoporous carbon materials with controllable structures and improved physicochemical properties by doping heteroatoms such as nitrogen into the carbon framework has attracted a lot of attention, especially in relation to energy storage and conversion. Herein, a series of nitrogen-doped mesoporous carbon spheres (NMCs) was synthesized via a facile dual soft-templating procedure by tuning the nitrogen content and carbonization temperature. Various physical and (electro)chemical properties of the NMCs have been comprehensively investigated to pave the way for a feasible design of nitrogen-containing porous carbon materials. The optimized sample showed a favorable electrocatalytic activity as evidenced by a high kinetic current and positive onset potential for oxygen reduction reaction (ORR) due to its large surface area, high pore volume, good conductivity, and high nitrogen content, which make it a highly efficient ORR metal-free catalyst in alkaline solutions.Bita Bayatsarmadi, YaoZheng, Mietek Jaroniec and Shi Zhang Qia

Recent advances in atomic metal doping of carbon-based nanomaterials for energy conversion

Nanostructured metal-contained catalysts are one of the most widely used types of catalysts applied to facilitate some of sluggish electrochemical reactions. However, the high activity of these catalysts cannot be sustained over a variety of pH ranges. In an effort to develop highly active and stable metal-contained catalysts, various approaches have been pursued with an emphasis on metal particle size reduction and doping on carbon-based supports. These techniques enhances the metal-support interactions, originating from the chemical bonding effect between the metal dopants and carbon support and the associated interface, as well as the charge transfer between the atomic metal species and carbon framework. This provides an opportunity to tune the well-defined metal active centers and optimize their activity, selectivity and stability of this type of (electro)catalyst. Herein, recent advances in synthesis strategies, characterization and catalytic performance of single atom metal dopants on carbon-based nanomaterials are highlighted with attempts to understand the electronic structure and spatial arrangement of individual atoms as well as their interaction with the supports. Applications of these new materials in a wide range of potential electrocatalytic processes in renewable energy conversion systems are also discussed with emphasis on future directions in this active field of research.Bita Bayatsarmadi, Yao Zheng, Anthony Vasileff and Shi-Zhang Qia

Highly stable Li⁺ selective electrode with metal-organic framework as ion-to-electron transducer

Detection of Li+ ions is vital due to their applications as therapeutic drugs in medicine. In addition, finding Li+ in geothermal brines is gaining interest because of its application in energy storage systems. Monitoring Li+ levels in an aqueous environment can be achieved using chemical sensors. Solid-contact sensors (SCS) have attracted significant attention because of their portability, high sensitivity and lack of requirement of calibration. However, most solid-contact sensors suffer from low stability, especially in the long term. As a result, ion-to-electron transducers have been utilized to mitigate this problem. Recently Metal-Organic Frameworks (MOFs) have proven to be excellent candidates for use as ion-to-electron transducers in SCSs. In this study, we have used Ni-HAB MOF to produce a highly stable Li+ selective electrode. Increasing the thickness of the MOF to 3.28 µm enhanced the sensor's capacitance 100-fold leading to the lowest drift in Li+ SCSs reported in the literature, 1.15×10−6 mV/h with a low limit of detection (LOD) of 9.94×10−7M and a 57.6 mV/dec sensitivity. The sensor exhibited a linear output and a fast response time of less than 1 s. In addition, the sensor developed was used in a real brine to detect the concentration of Li+ ions, where the obtained results were in good agreement with the actual concentration of Li+ ions. This paper offers a solution for the persistent issues of solid-contact sensors such as drift, response time, and limit of detection and paves the way for the miniaturization of sensors to be used in real-life applications

Significant enhancement of water splitting activity of N-carbon electrocatalyst by trace level co doping

Replacement of precious metal electrocatalysts with highly active and cost effi cient alternatives for complete water splitting at low voltage has attracted a growing attention in recent years. Here, this study reports a carbon-based composite co-doped with nitrogen and trace amount of metallic cobalt (1 at%) as a bifunctional electrocatalyst for water splitting at low overpotential and high current density. An excellent electrochemical activity of the newly developed electrocatalyst originates from its graphitic nanostructure and highly active Co-N x sites. In the case of carefully optimized sample of this electrocatalyst, 10 mA cm −2 current density can be achieved for two half reactions in alkaline solutions—hydrogen evolution reaction and oxygen evolution reaction—at low overpotentials of 220 and 350 mV, respectively, which are smaller than those previously reported for nonprecious metal and metalfree counterparts. Based on the spectroscopic and electrochemical investigations, the newly identifi ed Co-N x sites in the carbon framework are responsible for high electrocatalytic activity of the Co,N-doped carbon. This study indicates that a trace level of the introduced Co into N-doped carbon can signifi cantly enhance its electrocatalytic activity toward water splitting.Bita Bayatsarmadi, Yao Zheng, Youhong Tang, Mietek Jaroniec and Shi-Zhang Qia

Analytical characterisation of nanoscale zero-valent iron: A methodological review

© 2015 Elsevier B.V. Zero-valent iron nanoparticles (nZVI) have been widely tested as they are showing significant promise for environmental remediation. However, many recent studies have demonstrated that their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Both the mobility and reactivity of nZVI mainly depends on properties such as particle size, surface chemistry and bulk composition. In order to ensure efficient remediation, it is crucial to accurately assess and understand the implications of these properties before deploying these materials into contaminated environments. Many analytical techniques are now available to determine these parameters and this paper provides a critical review of their usefulness and limitations for nZVI characterisation. These analytical techniques include microscopy and light scattering techniques for the determination of particle size, size distribution and aggregation state, and X-ray techniques for the characterisation of surface chemistry and bulk composition. Example characterisation data derived from commercial nZVI materials is used to further illustrate method strengths and limitations. Finally, some important challenges with respect to the characterisation of nZVI in groundwater samples are discussed