Photo-assisted electrodeposition of MoS_xfrom ionic liquids on organic-functionalized silicon photoelectrodes for H₂generation

Abstract

This work reports the synergistic utility of ionic liquid-based, photo-assisted electrodeposition of MoS x onto organic-functionalized silicon photolelectrodes for dihydrogen (H 2 ) evolution under 1-sun illumination. The surface linker 3,5-dimethoxyphenyl covalently attached to Si(111) enhances conductivity at the substrate| electrolyte interface (impedance spectroscopy) and provides improved physico-chemical support for MoS x deposition (SEM, Raman, PEC-deposition, XPS), to generate a functional composite device that results in 0.33% efficiency for solar / H 2 conversion. We report a new method of ionic liquid-based MoS x deposition that avoids complications in analogous aqueous procedures and facilitates the deposition of a uniform catalytic film. This work provides a generalized framework for the optimization of non-platinum catalysts for solar / H 2 conversion.

Light-Driven Photocatalytic Hydrogen Evolution on Spindle-like MoSx Nanostructures Grown on Poly-Salicylic Acid Synthesized through Bipolar Electrochemistry

“…The importance of the PSA substrate is further confirmed when catalytic activity was investigated under light irradiation. PSA substrate offers a significant photocatalytic activity in the MoS x /PSA integrated system, similar to the other composite materials reported by many researchers. ,− For example, MoS 3 combined with triethanolamine has been used for photocatalytic HER . Redman et al .…”

“…The HER has more attracted attention than CO 2 reduction because of its simple operation and pathway with longer Faradaic efficiency. , Platinum (Pt) derivatives are among the most popular catalysts to accelerate HER from electrolysis of water or acidic aqueous solution; however, the high cost of Pt catalyst limited its widespread application . Recent research has demonstrated that nanosized molybdenum sulfide (MoS x , x is chiefly 2 or 3) has unique features like low cost, high stability, and catalytic activity toward HER and low cytotoxicity (even compared to graphene analogues). − Thin film MoS x has been considered as a catalyst for two decades, − and more recently, great attention has been paid to investigate the ratio of active edge sites per unit area aimed at enhancing its electrochemical and catalytic properties. ,,− Alongside the various production methods such as solvothermal synthesis, chemical, or physical vapor deposition and chemical or physical exfoliation, ,, the electrodeposition process has appeared as a promising way to fabricate thin films, − , a few layers or monolayers, ,,,, hollow shapes, and nanowires . However, the conventional electrochemical system suffers from some drawbacks such as being time-consuming and complex.…”

“…Recently, it has been demonstrated that amorphous MoS x possesses higher catalytic activity compared to the crystalline MoS x because of abundant active edge sites, , typically originating from the building blocks of [Mo 3 S 13 ] 2– clusters. − However, the electrocatalytic activity of MoS x can be improved through combination with a conductive or photoactive substrate. In this regard, reduced graphene oxide, , porous carbon aerogel, mesoporous carbon, or other carbon based structures, , polymers, , mesoporous organosilica nanosheets, , and so on have been used to enhance the applicability of MoS x . Interestingly, integration of transition metal chalcogenides (TMCs) with different metal–organic dyes, metal-free organic dyes, quantum dots, carbon substrates, and so on have displayed the characteristics of dye-synthesized photodevices. ,, Generally, a dye component connected with a metal derivative catalyst, which is able to convert photons to electrical energy and fuels, is termed as a dye-synthesized photocathode. , The extensive absorption band of sensitizers in combination with nanocrstalline transition metal derivatives have significantly harvested a large segment of light from the UV to the near IR region.…”

Benchmarking the Activity, Stability, and Inherent Electrochemistry of Amorphous Molybdenum Sulfide for Hydrogen Production

“…The edge sites‐driven hydrogen electroadsorption properties of TMDs have prompted the fabrication of amorphous molybdenum sulfide materials (MoS x ) to minimize exposure of the electrocatalytically inert MoS 2 basal planes for multiple applications . A simple, yet scalable method to fabricate MoS x has been reported by substrate‐insensitive electrodeposition from a [MoS 4 ] 2− precursor, and critical properties in MoS x materials such as film thickness, morphology, Mo:S stoichiometry, as well as incorporation of dopants or nanocomposite formation, have been easily tuned by experimental parameters.…”

Decoupling Effects of Surface Recombination and Barrier Height on p-Si(111) Photovoltage in Semiconductor|Liquid Junctions via Molecular Dipoles and Metal Oxides

“…Emitter layers function by maximizing the photovoltage ( V OC ) produced at the semiconductor solution junction by maximizing the built-in potential difference between the p and n + materials. , However, emitter layers are produced by high-temperature vapor infusion techniques, which are not easily applicable to polycrystalline semiconductors, or modulation of nanosized junctions and devices . To this end, our group − and others − have sought solution-based, low-temperature surface functionalization techniques to mimic the functionality of emitter layers using molecular structural specificity. Such techniques vary in their methods of functionalization at the semiconductor surface, but all rely on utilizing molecular electrostatic dipole moments to increase the barrier height (the thermodynamic barrier to thermionic emission) at the semiconductor junction, , thereby influencing the observed photovoltage under illumination.…”