Binary Cooperative Thermal Treatment of Cellulose and MoS₂ for the Preparation of Sustainable Paper-Based Electrochemical Devices for Hydrogen Evolution

Abstract

The simple, fast, scalable, and integrative preparation of sustainable electrodes using earth-abundant materials toward energy applications is a long-standing challenge. In this work, we attempted to achieve such features by developing a binary cooperative thermal process using cellulose sheets and molybdenum disulfide (MoS 2 ) toward hydrogen evolution reaction (HER). The thermal process converts cellulose into a highly conductive hydrophobic carbon-based material while generating chemical defects on MoS 2 . The latter is of fundamental importance to improve the catalytic activity for HER through activating the wellknown inert MoS 2 basal planes. Thermal desulfurization was confirmed by X-ray photoelectron spectroscopy, Kelvin probe force microscopy, Raman spectroscopy, and energy-dispersive Xray spectroscopy. Interestingly, a desulfurization gradient was observed at the MoS 2 particles, where the edges are more defective than the basal planes. The resulting defect-like MoS 2 particles are highly active toward HER. In addition, the porosity of paper enables simple filtration of catalysts and the possibility to tune the electrochemically active surface area by simply adding isopropanol before the electrolysis. Finally, we showed an ultrafast coating method using a commercial MoS 2 spray on sheets of paper that enables H 2 bubble generation at specific regions of the electrode. The overpotential (η) positively shifted more than 300 mV when compared with nontreated MoS 2 , reaching η = 240 mV to obtain 10 mA cm −2 of HER current density.

Tuning the Chemical and Electrochemical Properties of Paper-Based Carbon Electrodes by Pyrolysis of Polydopamine

“…The large current observed after PDA modification, e.g., ∼10× higher, is due to the hydrophilicity of the interface promoted by the addition of N and O groups. As demonstrated in contact angle measurements, the electrolyte penetrates into the bulk region of PP promoting an increase of the area of the electrodes that ultimately results in the large currents obtained. , , However, since PDA is not conductive, the Δ E p values are high in such conditions. Figure c shows a schematic illustration of the cross-sectional view of the electrodes.…”

Strain and defect-engineering on the basal plane of ultra-large MoS2 monolayers attached onto stretchable gold electrodes

“…To improve the performance in the region of the largest area of MoS 2 , many methods have been reported to create defects that ultimately work as catalytic sites. For example, batteries, 16 supercapacitors, 17 and electrochemical hydrogen production devices 18,19 can have their performance enhanced by introducing defects on the basal plane of MoS 2 . The most common types of defects introduced on the basal plane are sulfur vacancies or edge-like defects.…”

Redox exfoliated NbS2: characterization, stability, and oxidation

“…11 The main drawback of the latter, however, is the scarcity of reaction sites. 12 Group-V TMDs, on the other hand, possess a metallic character in their most stable phase, 13 and it has been shown that defects and imperfections cause specific rearrangements to their crystalline structure, which enhance adsorption/ desorption events. 7,8 These sites are more reactive than the basal plane and favor the catalytic activity for, e.g., HER; 10,11 moreover, it was also recently demonstrated that their high conductivity improves ionic mobility, facilitating some catalytic reactions.…”