Water-splitting photoelectrodes consisting of heterojunctions of carbon nitride with a-type low bandgap double perovskite oxide.

Quinary and senary non-stoichiometric double perovskites such as BaCaNbFeO(BCNF) have been utilized for gas sensing, solid oxide fuel cells and thermochemical COreduction. Herein, we examined their potential as narrow bandgap semiconductors for use in solar energy harvesting. A cobalt co-doped BCNF, BaCaNbFeCoO(BCNFCo), exhibited an optical absorption edge at ∼800 nm,-type conduction and a distinct photoresponse up to 640 nm while demonstrating high thermochemical stability.

Unusual Surface Ligand Doping-Induced p-Type Quantum Dot Solids and Their Application in Solar Cells.

Doping quantum dots (QDs) is a problem that has been haunting researchers in the QD research community for years, even though doping techniques have been utilized for decades in conventional semiconductors. For the "self-purification" in colloidal QDs, engineering the surface ligands has emerged as an effective way to alter free carrier concentrations and doping types in colloidal QD solids. Halide-atomic ligands are the most popular ligands in producing PbS QD solids since they provide minimal dot-to-dot distance while maintain low in-gap trap states.

Consistently High Values in p-i-n Type Perovskite Solar Cells Using Ni-Doped NiO Nanomesh as the Hole Transporting Layer.

Leading edge p-i-n type halide perovskite solar cells (PSCs) severely underperform n-i-p PSCs. p-i-n type PSCs that use PEDOT:PSS hole transport layers (HTLs) struggle to generate open-circuit photovoltage values higher than 1 V. NiO HTLs have shown greater promise in achieving high values albeit inconsistently.

Heterojunctions of halogen-doped carbon nitride nanosheets and BiOI for sunlight-driven water-splitting.

A fluorine-doped, chlorine-intercalated carbon nitride (CNF-Cl) photocatalyst has been synthesized for simultaneous improvements in light harvesting capability along with suppression of charge recombination in bulk g-CN. The formation of heterojunctions of these CNF-Cl nanosheets with low bandgap, earth abundant bismuth oxyiodide (BiOI) was achieved, and the synthesized heterojunctions were tested as active photoanodes in photoelectrochemical water splitting experiments. BiOI/CNF-Cl heterojunctions exhibited extended light harvesting with a band-edge of 680 nm and generated photocurrent densities approaching 1.

Vapor growth of binary and ternary phosphorus-based semiconductors into TiO nanotube arrays and application in visible light driven water splitting.

We report successful synthesis of low band gap inorganic polyphosphide and TiO heterostructures with the aid of short-way transport reactions. Binary and ternary polyphosphides (NaP, SnIP, and (CuI)P) were successfully reacted and deposited into electrochemically fabricated TiO nanotubes. Employing vapor phase reaction deposition, the cavities of 100 μm long TiO nanotubes were infiltrated; approximately 50% of the nanotube arrays were estimated to be infiltrated in the case of NaP.

CN: A Low Bandgap Semiconductor Containing an Azo-Linked Carbon Nitride Framework for Photocatalytic, Photovoltaic and Adsorbent Applications.

Modification of carbon nitride based polymeric 2D materials for tailoring their optical, electronic and chemical properties for various applications has gained significant interest. The present report demonstrates the synthesis of a novel modified carbon nitride framework with a remarkable 3:5 C:N stoichiometry (CN) and an electronic bandgap of 1.76 eV, by thermal deammoniation of the melem hydrazine precursor.

Enhanced charge separation in g-CN-BiOI heterostructures for visible light driven photoelectrochemical water splitting.

Heterojunctions of the low bandgap semiconductor bismuth oxyiodide (BiOI) with bulk multilayered graphitic carbon nitride (g-CN) and few layered graphitic carbon nitride sheets (g-CN-S) are synthesized and investigated as an active photoanode material for sunlight driven water splitting. HR-TEM and elemental mapping reveals formation of a unique heterostructure between BiOI platelets and the carbon nitride (g-CN and g-CN-S) network that consisted of dendritic BiOI nanoplates surrounded by g-CN sheets. The presence of BiOI in g-CN-S/BiOI and g-CN-S/BiOI nanocomposites extends the visible light absorption profile from 500 nm up to 650 nm.

Preferentially oriented TiO nanotube arrays on non-native substrates and their improved performance as electron transporting layer in halide perovskite solar cells.

Anodically formed TiO nanotube arrays (TNTAs) constitute an optoelectronic platform that is being studied for use as a photoanode in photoelectrocatalytic cells, as an electron transport layer (ETL) in solar cells and photodetectors, and as an active layer for chemiresistive and microwave sensors. For optimal transport of charge carriers in these one-dimensional polycrystalline ordered structures, it is desirable to introduce a preferential texture with the grains constituting the nanotube walls aligned along the transport direction. Through x-ray diffraction analysis, we demonstrate that choosing the right water content in the anodization electrolyte and the use of a post-anodization zinc ion treatment can introduce a preferential texture in sub-micron length transparent TNTAs formed on non-native substrates.

A review on photocatalytic CO reduction using perovskite oxide nanomaterials.

As the search for efficient catalysts for CO photoreduction continues, nanostructured perovskite oxides have emerged as a class of high-performance photocatalytic materials. The perovskite oxide candidates for CO photoreduction are primarily nanostructured forms of titanates, niobates, tantalates and cobaltates. These materials form the focus of this review article because they are much sought-after due to their nontoxic nature, adequate chemical stability, and tunable crystal structures, bandgaps and surface energies.

Heterojunctions of mixed phase TiO nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity.

Anodically formed, vertically oriented, self-organized cylindrical TiO nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs.

Halide perovskite solar cells using monocrystalline TiO nanorod arrays as electron transport layers: impact of nanorod morphology.

This is the first report of a 17.6% champion efficiency solar cell architecture comprising monocrystalline TiO nanorods (TNRs) coupled with perovskite, and formed using facile solution processing without non-routine surface conditioning. Vertically oriented TNR ensembles are desirable as electron transporting layers (ETLs) in halide perovskite solar cells (HPSCs) because of potential advantages such as vectorial electron percolation pathways to balance the longer hole diffusion lengths in certain halide perovskite semiconductors, ease of incorporating nanophotonic enhancements, and optimization between a high contact surface area for charge transfer (good) versus high interfacial recombination (bad).

One-Dimensional Electron Transport Layers for Perovskite Solar Cells.

The electron diffusion length () is smaller than the hole diffusion length () in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs.