Self-assembled 2D WSe2 thin films for photoelectrochemical hydrogen production.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 26126745.
- Also identified by DOI 10.1038/ncomms8596 and PMC identifier 4506493.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
WSe2--a layered semiconductor that can be exfoliated into atomically thin two-dimensional sheets--offers promising characteristics for application in solar energy conversion. However, the lack of controllable, cost-effective methods to scalably fabricate homogeneous thin films currently limits practical application. Here we present a technique to prepare controlled thin films of 2D WSe2 from dispersions of solvent-exfoliated few-layer flakes. Flake self-assembly at a liquid/liquid interface (formed exceptionally from two non-solvents for WSe2) followed by substrate transfer affords large-area thin films with superior 2D flake alignment compared with traditional (liquid/air) self-assembly techniques. We further demonstrate, for the first time, solar-to-hydrogen conversion from solution-processed WSe2 thin films. Bare photoelectrodes with a thickness of ca. 25 nm exhibit sustained p-type photocurrent under simulated solar illumination, and up to 1.0 mA cm(-2) at 0 V versus reversible hydrogen electrode with an added water reduction catalyst (Pt). The importance of the self-assembled morphology is established by photoelectrochemical and conductivity measurements.