44 research outputs found
The Selective Electrochemical Conversion of Preactivated CO_2 to Methane
This work reports the selective electrochemical conversion of CO_2 to methane, the reverse reaction of fossil fuel combustion. This reaction is facilitated by preactivation of the CO_2 molecule with an N-heterocyclic carbene (NHC) to form a zwitterionic species in the first step. In the presence of Ni(cyclam)^(2+) and CF_3CH_2OH, this species is shown to undergo further electrochemical reduction of the bound-CO_2 fragment at glassy carbon cathodes in dichloromethane electrolyte solution. Labeling studies confirm the origin of the carbon and protons in the methane product are the preactivated CO_2 and trifluoroethanol respectively
Disulfides – Effective radical generators for flame retardancy of polypropylene
The potential of thirteen aliphatic, aromatic, thiuram and heterocyclic substituted organic disulfide derivatives of the general formula R-S-S-R’ as a new group of halogen-free flame retardants (FR) for polypropylene films have been investigated. According to DIN 4102-1 standard ignitibility test, for the first time it has been demonstrated that many of the disulfides alone can effectively provide flame retardancy and self-extinguishing properties to polypropylene (PP) films at already very low concentrations of 0.5 wt%. In an effort to elucidate the mechanism of the thermal decomposition of disulfide derivatives the fragmentation patterns of the evolved gases from a thermogravimetric analyzer (TGA) have been analyzed by simultaneous mass spectrometry (MS) and Fourier transform infrared spectrometry (FTIR). The main decomposition products initiated by homolytic scission of the S-S bond and/or scission of the C-S bond were identified as thiols, aliphatic and aromatic hydrocarbons, isothiocyanates (depending on the disulfide structures) with further evolution of elemental sulfur and sulfur dioxide at temperatures of above 300 oC and 450 oC, respectively. Based on this preliminary study, we have shown that disulfides represented by e.g. diphenyl disulfide (1), 5,5'-dithiobis(2-nitrobenzoic acid) (2), bis(1-phenyl-1H-tetrazol-5yl)-disulfide (4), 2-bisbenzothiazole-2,2′-disulfide (6) and N,N-dithiobis-(phtalimide) (10) constitute a new halogen-free family of additives for flame retarding of polypropylene
Robust production of purified H-2 in a stable, self-regulating, and continuously operating solar fuel generator
The development of practical solar-driven electrochemical fuel generators requires the integration of light absorbing and electrochemical components into an architecture that must also provide easy separation of the product fuels. Unfortunately, many of these components are not stable under the extreme pH conditions necessary to facilitate ionic transport between redox reaction sites. By using a controlled recirculating stream across reaction sites, this work demonstrates a stable, self-regulating and continuous purified solar-hydrogen generation from near neutral pH electrolytes that yield continuous nearly pure H-2 streams with solar-fuel efficiencies above 6.2%
Discovery, benchmarking, characterization and integration of new materials for solar-fuels generators
The Joint Center for Artificial Photosynthesis (JCAP) was established in 2010 as a U.S. Department of Energy
(DOE) Energy Innovation Hub. The JCAP mission is to demonstrate a scalable, integrated solar-fuels generator,
which uses Earth-abundant elements and (with no wires) robustly produces fuel from the sun 10 times more
efficiently than (current) crops. This presentation will describe how JCAP researchers use both directed and
high-throughput approaches to discover light absorbers and catalysts for artificial photosynthesis, and how the
performance of new materials is compared to known materials using rigorous benchmarking protocols. By
using advanced characterization and computational techniques to understand and improve performance,
promising materials are assembled into integrated structures that can be reliably produced and incorporated
into scalable prototypes
The Effects of Surface Energetics on the Cyclic Voltammetry of Metallocenes at Nonilluminated n ‐ InP Electrodes
Luquid membranes with light switches
Separation of solutes with liquid membranes becomes a powerful tool when the solute carriers are selectively activated photochemically
Ferrocene as an internal standard for electrochemical measurements
Electrochemistry is an increasingly popular technique for the characterization of new compounds. The basic thermodynamic quantity that is assigned to an electrode process is the standard or formal reduction potential (E^o or E^f). In aqueous solution the measurement of reduction potentials is facilitated by the use of reliable and universally accepted reference electrodes such as the normal hydrogen electrode (NHE) or the saturated calomel electrode (SCE). In many instances electrochemical measurements in water are impossible due to insolubility or instability of the compound. Unfortunately, no universal reference electrode exists for nonaqueous solvents
Electrochemistry, Stability, and Alkene Complexation Chemistry of Copper(I) Triflate in Aqueous Solution. Potential for Use in Electrochemically Modulated Complexation-Based Separation Processes
Ferrocene as an internal standard for electrochemical measurements
Electrochemistry is an increasingly popular technique for the characterization of new compounds. The basic thermodynamic quantity that is assigned to an electrode process is the standard or formal reduction potential (E^o or E^f). In aqueous solution the measurement of reduction potentials is facilitated by the use of reliable and universally accepted reference electrodes such as the normal hydrogen electrode (NHE) or the saturated calomel electrode (SCE). In many instances electrochemical measurements in water are impossible due to insolubility or instability of the compound. Unfortunately, no universal reference electrode exists for nonaqueous solvents