Significant effort is currently focused on microbial fuel cells (MFCs) as a source of renewable energy. Most studies concentrate on operation at mesophilic temperatures. However, anaerobic digestion studies have reported on the superiority of thermophilic operation and demonstrated a net energy gain in terms of methane yield. As such, our studies focused on MFC operation and microbiology at 55 1C. Over a 100-day operation, these MFCs were stable and achieved a power density of 37 mW m À2 with a coulombic efficiency of 89%. To infer activity and taxonomic identity of dominant members of the electricity-producing community, we performed phylogenetic microarray and clone library analysis with small subunit ribosomal RNA (16S rRNA) and ribosomal RNA gene (16S rDNA). The results illustrated the dominance (80% of clone library sequences) of the Firmicutes in electricity production. Similarly, rRNA sequences from Firmicutes accounted for 50% of those taxa that increased in relative abundance from current-producing MFCs, implying their functional role in current production. We complemented these analyses by isolating the first organisms from a thermophilic MFC. One of the isolates, a Firmicutes Thermincola sp. strain JR, not only produced more current than known organisms (0.42 mA) in an H-cell system but also represented the first demonstration of direct anode reduction by a member of this phylum. Our research illustrates the importance of using a variety of molecular and culture-based methods to reliably characterize bacterial communities. Consequently, we revealed a previously unidentified functional role for Gram-positive bacteria in MFC current generation.

Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO2 reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field.

Adsorbed molecules can significantly affect the properties of atomically thin materials. Physisorbed water plays a significant role in altering the optoelectronic properties of single‐layer MoS2, one such 2D film. Here the distinct quenching effect of adsorbed water on the photoluminescence of single‐layer MoS2 is demonstrated through scanning‐probe and optical microscopy.

The synthesis of boron difluoride complexes of as eries of curcuminoidd erivatives containing various donor end groups is described. Time-dependent (TD)-DFT calculations confirm the charge-transfer character of the second lowest-energy transition band and ascribe the lowest energy band to a" cyanine-like" transition. Photophysical studies reveal that tuning the donors trengtho ft he end groups allows coveringab road spectral range, from the visible to the NIR region, of the UV-visible absorptiona nd fluorescence spectra.T wo-photon-excited fluorescence and Z-scan techniques prove that an increase in the donor strengtho r in the rigidity of the backboner esultsi naconsiderable increase in the two-photon cross section, reaching 5000 GM, with predominant two-photona bsorption from the S 0 -S 2 charge-transfer transition. Direct comparisons with the hemicurcuminoid derivatives show that the two-photon active band for the curcuminoid derivatives has the same intramolecular charge-transfer character and therefore arises from ad ipolar structure. Overall,t his structure-relationship study allowst he optimization of the two-photon brightness (i.e., 400-900GM) with one dye that emits in the NIR region of the spectrum.I na ddition, these dyes demonstrate high intracellularu ptakee fficiencyi nC os7 cells with emission in the visible region, which is further improved by using porous silican anoparticles as dye vehicles for the imaging of two mammalian carcinomac ells type based on NIR fluorescence emission.

Photoelectrochemical (PEC) water splitting has the potential to significantly reduce the costs associated with electrochemical hydrogen production through the direct utilization of solar energy. Many PEC cells utilize liquid electrolytes that are detrimental to the durability of the photovoltaic (PV) or photoactive materials at the heart of the device. The membrane-electrode-assembly (MEA) style, PEC cell presented herein is a deviation from that paradigm as a solid electrolyte is used, which allows the use of a water vapor feed. The result of this is a correspondent reduction in the amount of liquid and electrolyte contact with the PV, thereby opening the possibility of longer PEC device lifetimes. In this study, we demonstrate the operation of a liquid and vapor-fed PEC device utilizing a commercial III-V photovoltaic that achieves a solar-to-hydrogen (STH) efficiency of 7.5% (12% as a PV-electrolyzer). While device longevity using liquid water was limited to less than 24 hours, replacement of reactant with water vapor permitted 100 hours of continuous operation under steady-state conditions and diurnal cycling. Key findings include the observations that the exposure of bulk water or water vapor to the PV must be minimized, and that operating in mass-transport limited regime gave preferable performance.