MoS2 is a two-dimensional material that is gaining prominence due to its unique electronic and chemical properties. Here, we demonstrate ligand conjugation of chemically exfoliated MoS2 using thiol chemistry. Using this method, we modulate the zeta-potential and colloidal stability of MoS2 sheets through ligand designs, thus enabling its usage as a selective artificial protein receptor for β-galactosidase. The facile thiol functionalization route opens the door for surface modifications of solution processable MoS2 sheets.

Here, we report that transition-metal dichalcogenides such as MoS2 and WS2 can be decorated with gold nanoparticles by a spontaneous redox reaction with hexachloroauric acid in water. The resulting gold nanoparticles tend to grow at defective sites, and therefore, selective decorations at the edges and the line defects in the basal planes of bulk single crystals were observed. The lithium intercalation-exfoliation process makes the basal planes of chemically exfoliated MoS2 and WS2 sheets much more defective than their single-crystalline counterparts, leading to a more uniform and higher-density deposition of gold nanoparticles. Due to the greatly improved charge transport between adjacent sheets, the resulting MoS2/Au and WS2/Au hybrids show significantly enhanced electrocatalytic performance toward hydrogen evolution reactions.

The Material properties of BiVO4 are modified via coupling with a SnO2 buffer layer inserted between BiVO4 and a FTO substrate.

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Recently, the trend in inverted hybrid perovskite solar cells (PVSCs) has been to utilize NiO as hole transport layers. However, the majority of reported solution-processed NiO films require a high-temperature thermal annealing process, which is unfavorable for large-scale manufacturing and suffers from lack of uniformity. We report, for the first time, e-beam evaporation as a low-temperature vacuum process for the deposition of NiO hole transport layers for PVSCs. Device characterization shows that efficiency is on par with solution-processed methods, the highest efficiency at 15.4% with no obvious hysteresis. Differences are found to be due to the presence of more Ni in e-beam evaporated NiO, which are responsible for a lower transmittance but higher conductivity. Most importantly, e-beam-evaporated NiO-based PVSCs show greater uniformity and reproducibility compared to spin-coated NiO-based PVSCs. Finally, e-beam-evaporated NiO has the additional advantage of being produced by a low-temperature deposition process and applicable over large areas. This work, therefore, represents a significant step toward large-area PVSCs, where e-beam evaporation can be used for the low-temperature uniform deposition of charge-transport layers, such as NiO.

The photoelectrochemical (PEC) properties of a Cu(In,Ga)Se2 (CIGS) photocathode covered with reduced graphene oxide (rGO) as a catalyst binder for solar‐driven hydrogen evolution are reported. Chemically reduced rGO with various concentrations is deposited as an adhesive interlayer between CIGS/CdS and Pt. PEC characteristics of the CIGS/CdS/rGO/Pt are improved compared to the photocathode without rGO due to enhancement of charge transfer via efficient lateral distribution of photogenerated electrons by conductive rGO to the Pt. More importantly, the introduction of rGO to the CIGS photocathode significantly enhances the PEC stability; in the absence of rGO, a rapid loss of PEC stability is observed in 2.5 h, while the optimal rGO increases the PEC stability of the CIGS photocathode for more than 7 h. Chemical and structural characterizations show that the loss of the Pt catalyst is one of the main reasons for the lack of long‐term PEC stability; the introduction of rGO, which acts as a binder to the Pt catalysts by providing anchoring sites in the rGO, results in complete conservation of the Pt and hence much enhanced stability. Multiple functionality of rGO as an adhesive interlayer, an efficient charge transport layer, a diffusion barrier, and protection layer is demonstrated.

No abstract

Cresols are a group of naturally occurring and massively produced methylphenols with broad use in the chemical industry. Here, we report that -cresol and its liquid mixtures with other isomers are surprisingly good solvents for processing carbon nanotubes. They can disperse carbon nanotubes of various types at unprecedentedly high concentrations of tens of weight percent, without the need for any dispersing agent or additive. Cresols interact with carbon nanotubes by charge transfer through the phenolic hydroxyl proton and can be removed after processing by evaporation or washing, without altering the surface of carbon nanotubes. Cresol solvents render carbon nanotubes polymer-like rheological and viscoelastic properties and processability. As the concentration of nanotubes increases, a continuous transition of four states can be observed, including dilute dispersion, thick paste, free-standing gel, and eventually a kneadable, playdough-like material. As demonstrated with a few proofs of concept, cresols make powders of agglomerated carbon nanotubes immediately usable by a broad array of material-processing techniques to create desirable structures and form factors and make their polymer composites.