Temperature and Pressure Dependence of Hydrothermal Electrodeposition of Molybdenum Sulfide

Due to their diverse chemical, physical, and electronic properties, metal chalcogenides, especially metal disulfides, are considered key components in energy conversion devices. Here, we report the control of the local atomic structure of molybdenum disulfide (MoS₂) and its application toward enhanced selectivity of electrochemical carbon dioxide (CO₂) reduction. The control of the atomic structure of MoS₂ was achieved by using a recently developed hydrothermal electrochemical flow reactor, which allows independent control of the deposition temperature and pressure. Material characterization using synchrotron X-ray pair distribution function, X-ray absorption fine structure analysis, and Raman spectroscopy revealed that the Mo–S bond length and the density of sulfur vacancies are controlled by temperature and pressure of electrodeposition (temperature: 25 and 120 °C, pressure: 1, 2, and 4 MPa). The advantage of this approach was manifested by the improved selectivity for CO₂ reduction, which was correlated with the Mo–S bond lengthening as demonstrated by the density functional theory calculation. These results offer intriguing synthetic approaches of metal sulfide-based electrocatalysts with desired chemical activity.