Operando Synthesis of Macroporous Molybdenum Diselenide Films for Electrocatalysis of the Hydrogen-Evolution Reaction
Abstract
The catalytically inactive components of a film have been converted, through an operando method of synthesis, to produce a catalyst for the reaction that the film is catalyzing. Specifically, thin films of molybdenum diselenide have been synthesized using a two-step wet-chemical method, in which excess sodium selenide was first added to a solution of ammonium heptamolydbate in aqueous sulfuric acid, resulting in the spontaneous formation of a black precipitate that contained molybdenum triselenide (MoSe_3), molybdenum trioxide (MoO_3), and elemental selenium. After purification and after the film had been drop cast onto a glassy carbon electrode, a reductive potential was applied to the precipitate-coated electrode. Hydrogen evolution occurred within the range of potentials applied to the electrode, but during the initial voltammetric cycle, an overpotential of ~400 mV was required to drive the hydrogen-evolution reaction at a benchmark current density of −10 mA cm^(–2). The overpotential required to evolve hydrogen at the benchmark rate progressively decreased with subsequent voltammetry cycles, until a steady state was reached at which only ~250 mV of overpotential was required to pass −10 mA cm^(–2) of current density. During the electrocatalysis, the catalytically inactive components in the as-prepared film were (reductively) converted to MoSe_2 through an operando method of synthesis of the hydrogen-evolution catalyst. The initial film prepared from the precipitate was smooth, but the converted film was completely covered with pores ~200 nm in diameter. The porous MoSe_2 film was stable while being assessed by cyclic voltammetry for 48 h, and the overpotential required to sustain 10 mA cm^(–2) of hydrogen evolution increased by <50 mV over this period of operation.
Additional Information
© 2014 American Chemical Society. Received: December 16, 2013. Revised: July 17, 2014. Published: July 17, 2014. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a U.S. Department of Energy (DOE) Energy Innovation Hub, supported through the Office of Science of the DOE via Grant DE-SC0004993. A.I.C. acknowledges a National Science Foundation Graduate Research Fellowship for support.Attached Files
Supplemental Material - cs500412u_si_001.pdf
Files
Name | Size | Download all |
---|---|---|
md5:9c065af3f518d9b9fa3c0a24a1e352f7
|
2.0 MB | Preview Download |
Additional details
- Eprint ID
- 47873
- Resolver ID
- CaltechAUTHORS:20140804-090046189
- Department of Energy (DOE)
- DE-SC0004993
- NSF Graduate Research Fellowship
- Created
-
2014-08-04Created from EPrint's datestamp field
- Updated
-
2023-06-01Created from EPrint's last_modified field
- Caltech groups
- JCAP