Electrospun polymer fibers containing poly(methyl methacrylate) (PMMA), Ti(OH)4, and UiO-66 convert a chemical warfare agent simulant to non-toxic product via catalytic hydrolysis.
Electrocatalytic ammonia oxidation
at room temperature and pressure
allows energy-economical and environmentally friendly production of
nitrites and nitrates. Few molecular catalysts, however, have been
developed for this six- or eight-electron oxidation process. We now
report [Cu(bipyalk)]+, a homogeneous electrocatalyst that
realizes the title reaction in water at 94% Faradaic efficiency. The
catalyst exhibits high selectivity against water oxidation in aqueous
media, as [Cu(bipyalk)]+ is not competent for water oxidation.
One ongoing challenge in the field of iridium-based water oxidation catalysts is to develop a molecular precatalyst affording well-defined homogeneous active species for catalysis. Our previous work by using organometallic precatalysts Cp*Ir(pyalk)-OH and Ir(pyalk)(CO) 2 (pyalk = (2-pyridyl)-2-propanolate) suggested a μ-oxo-bridged Ir dimer as the probable resting state, although the structure of the active species remained elusive. During the activation, the ligands Cp* and CO were found to oxidatively degrade into acetic acid or other products, which coordinate to Ir centers and affect the catalytic reaction. Two related dimers bearing two pyalk ligands on each iridium were crystallized for structural analysis. However, preliminary results indicated that these crystallographically characterized dimers are not active catalysts. In this work, we accessed a mixture of dinuclear iridium species from a coordination precursor, Na[Ir(pyalk)Cl 4 ], and assayed their catalytic activity for oxygen evolution by using NaIO 4 as the oxidant. This catalyst showed comparable oxygen-evolution activity to the ones previously reported from organometallic precursors without demanding oxidative activation to remove sacrificial ligands. Future research along this direction is expected to provide insights and design principles toward a well-defined active species.
The
development of light-harvesting architectures with broad absorption
coverage in the visible region continues to be an important research
area in the field of artificial photosynthesis. Here, we introduce
a new class of ethynyl-linked panchromatic dyads composed of dibenzophenazines
coupled ortho and meta to tetrapyrroles
with an anchoring group that can be grafted onto metal oxide surfaces.
Quantum chemical calculations and photophysical measurements of the
synthesized materials reveal that both of the dibenzophenazine dyads
absorb broadly from 300 to 636 nm and exhibit absorption bands different
from those of the constituent chromophore units. Moreover, the different
points of attachment of dibenzophenazines to tetrapyrroles give different
absorption profiles which computations suggest result from differences
in the planarity of the two dyads. Applicability of the dyads in artificial
photosynthesis systems was assessed by their incorporation and characterization
of their performance in dye-sensitized solar cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.