2 research outputs found
Heterogeneous Electrochemical Ammonia Oxidation with a Ru-bda Oligomer Anchored on Graphitic Electrodes via CHâĎ Interactions
Molecular catalysts can promote ammonia oxidation, providing
mechanistic
insights into the electrochemical N2 cycle for a carbon-free
fuel economy. We report the ammonia oxidation activity of carbon anodes
functionalized with the oligomer {[RuII(bda-Îş-N2O2)(4,4â˛-bpy)]10(4,4â˛-bpy)}, Rubda-10, where bda is [2,2â˛-bipyridine]-6,6â˛-dicarboxylate
and 4,4â˛-bpy is 4,4â˛-bipyridine. Electrocatalytic studies
in propylene carbonate demonstrate that the Ru-based hybrid anode
used in a 3-electrode configuration transforms NH3 to N2 and H2 in a 1:3 ratio with near-unity faradaic
efficiency at an applied potential of 0.1 V vs Fc+/0, reaching
turnover numbers of 7500. X-ray absorption spectroscopic analysis
after bulk electrolysis confirms the molecular integrity of the catalyst.
Based on computational studies together with electrochemical evidence,
ammonia nucleophilic attack is proposed as the primary pathway that
leads to critical NâN bond formation
Photoinduced Current Transient Spectroscopy on Metal Halide Perovskites: Electron Trapping and Ion Drift
Metal halide perovskites (MHPs) are disruptive materials
for a
vast class of optoelectronic devices. The presence of electronic trap
states has been a tough challenge in terms of characterization and
thus mitigation. Many attempts based on electronic spectroscopies
have been tested, but due to the mixed electronicâionic nature
of MHP conductivity, many experimental results retain a large ambiguity
in resolving electronic and ionic charge contributions. Here we adapt
a method, previously used in highly resistive inorganic semiconductors,
called photoinduced current transient spectroscopy (PICTS) on lead
bromide 2D-like ((PEA)2PbBr4) and standard â3Dâ
(MAPbBr3) MHP single crystals. We present two conceptually
different outcomes of the PICTS measurements, distinguishing the different
electronic and ionic contributions to the photocurrents based on the
different ion drift of the two materials. Our experiments unveil deep
level trap states on the 2D, âion-frozenâ (PEA)2PbBr4 and set new boundaries for the applicability
of PICTS on 3D MHPs