CuBi2O4 is a multinary p-type semiconductor that has recently been identified as a promising photocathode material for photoelectrochemical (PEC) water splitting. It has an optimal bandgap energy (∼1.8 eV) and an exceptionally positive photocurrent onset potential (>1 V vs RHE), making it an ideal candidate for the top absorber in a dual absorber PEC device. However, photocathodes made from CuBi2O4 have not yet demonstrated high photoconversion efficiencies, and the factors that limit the efficiency have not yet been fully identified. In this work we characterize CuBi2O4 photocathodes synthesized by a straightforward drop-casting procedure and for the first time report many of the quintessential material properties that are relevant to PEC water splitting. Our results provide important insights into the limitations of CuBi2O4 in regards to optical absorption, charge carrier transport, reaction kinetics, and stability. This information will be valuable in future work to optimize CuBi2O4 as a PEC material. ...

Comprehensive Evaluation of CuBi2O4 as a Photocathode Material for Photoelectrochemical Water Splitting

This review article addresses areas where solid-state chemistry concepts can contribute to the on-going search for a “magic bullet” inorganic semiconductor that can efficiently split water or reduce CO2. First, a methodology to visualize complex ternary oxide combinations is outlined using 31 examples based on copper in both +1 and +2 oxidation states. Then the synthetic aspects are reviewed followed by a discussion of the structural characteristics. The optoelectronic aspects are considered next, culminating the review with the state-of-the-art in the practical applicability of these materials in solar fuels photogeneration and environmental (e.g., azo dye) remediation. © The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0271804jes]

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Review—copper oxide-based ternary and quaternary oxides: where solid-state chemistry meets photoelectrochemistry

The frequency dependent dielectric constant and loss of the unconventional bismuth cuprate glasses have been presented in wide temperature and frequency ranges. Alternating current dielectric loss peak has been observed in the measurable frequency range at higher temperatures, where the measured ac conductivity approaches the dc conductivity. The temperature range where ac loss peak has been observed, varies systematically with glass composition. The dielectric data at these temperature ranges have been analyzed in terms of different theoretical models to find out the possible relaxation mechanism. It has been observed that the dipolar relaxation model with a distribution of relaxation times can best explain the experimental data. The dipolar relaxation occurs due to the hopping of charge carriers between different localized valence states of copper ions within a range of energies near the mobility edge. High value of the dielectric constant observed in these glasses can be attributed to the influence of ...

Electrical relaxation mechanism in unconventional bismuth cuprate glasses

As CuBi2O4 is an emerging p-type semiconductor for applications as a photocathode in photoelectrochemical (PEC) solar fuel production, there is much to be understood about the uniqueness and common...

CuBi2O4: Electronic Structure, Optical Properties, and Photoelectrochemical Performance Limitations of the Photocathode

A novel bifunctional cathode for the generation and activation of H2O2 in electro-Fenton: Characteristics and mechanism

Temperature and compositional dependence of the electrical transport properties of the nonconventional binary bismuth cuprate glasses are reported for the first time. It has been observed that the phonon assisted small polaron hopping model in the nonadiabatic regime is consistent with the data only at high temperatures. The variable range hopping model can fit the low temperature data qualitatively. The polaron hopping models proposed by Schnakenberg [Phys. Status Solidi 28, 623 (1968)] and Emin [Phys. Rev. Lett. 32, 303 (1974)] can predict quantitatively the conductivity data in the entire temperature range of measurement for all glass compositions. The physical parameters obtained from the best fits of these models are found reasonable and consistent with the glass compositions.

http://repository.ias.ac.in/72859/1/52-PUB.pdf

Transport mechanism in nonconventional bismuth cuprate glass

The electronic structure and core level spectra of chlorogallium-phthalocyanine (ClGaPc) molecules of different thickness (submonolayer to multilayer) adsorbed on polycrystalline Au substrate and h...

Evolution of Electronic Structures of Polar Phthalocyanine-Substrate Interfaces

Stearic acid mediated growth of edge-on oriented bilayer poly(3-hexylthiophene) Langmuir films

A flexible, 2-fold interpenetrated 3D supramolecular structure [Cu(ndc 2 − )(1,10-phen)] n (where ndc 2 − = 2 ,6-napthalenedicarboxylate and 1,10-phen = 1,10-phenanthroline) comprising neutral 2D metal–organic layers as the basic building block was prepared. Structural study reveals that metal ions are bridged by ndc 2 − ligands to form 2D coordination layers and the coordinated 1,10-phen moieties are hanging from the layers in the interlamellar spaces. The gliding motion of π ⋯ π stacked layers through 1,10-phen moieties was found to be responsible for the flexibility of MOF and the consequent extended conjugation also rendered semiconducting behaviour in the material. Thermal stability studies revealed that the framework was pretty stable below 260°C. Additionally, the MOF was characterized by performing BET adsorption and photoluminescence studies. Further, the MOF was calcinated at 650°C to prepare well defined, nearly uniform and spherical shaped CuO nanoparticles (CuO-NPs) with an average size of ∼ 25 nm. Interestingly, CuO-NPs showed around 16 times more conductivity (4.8 × 10−2 S/cm) in relative to the parent MOF (3 x 10−3 S/cm). CuO-NPs induced cross-coupling reactions of alcohols and thiols with arylhalides have been reported. A simple, general, ligand-free and solvent-free procedure for the efficient synthesis of the cross-coupled products in high yield was successfully demonstrated.

Design of π-conjugated flexible semiconductive 2D MOF and MOF derived CuO nano-spheres for solvent free C-X (S, O) hetero-coupling catalysis with enhanced conductivity

Subhankar Mandal

Papers

Transport mechanism in nonconventional bismuth cuprate glass

Evolution of Electronic Structures of Polar Phthalocyanine-Substrate Interfaces

Stearic acid mediated growth of edge-on oriented bilayer poly(3-hexylthiophene) Langmuir films

Design of π-conjugated flexible semiconductive 2D MOF and MOF derived CuO nano-spheres for solvent free C-X (S, O) hetero-coupling catalysis with enhanced conductivity