New Simultaneous Exfoliation and Doping Process for Generating MX₂ Nanosheets for Electrocatalytic Hydrogen Evolution Reaction

Abstract

Doping nonmetal atoms into layered transition metal dichalcogenide MX2 structures has emerged as a promising strategy for enhancing their catalytic activities for the hydrogen evolution reaction. In this study, we developed a new and efficient one-step approach that involves simultaneous plasma-induced doping and exfoliating of MX2 bulk into nanosheets–such as MoSe2, WSe2, MoS2, and WS2 nanosheets–within a short time and at a low temperature (ca. 80 °C). Specifically, by utilizing active plasma that is generated with an asymmetric electrical field during the electrochemical reaction at the surface of the submerged cathode tip, we are able to achieve doping of nitrogen atoms, from the electrolytes, into the semiconducting 2H-MX2 structures during their exfoliation process from the bulk states, forming N-doped MX2. We selected N-doped MoS2 nanosheets for demonstrating their catalytic hydrogen evolution potential. We modulated the electronic and transport properties of the MoS2 structure with the synergy of nitrogen doping and exfoliating for enhancing their catalytic activity. We found that the nitrogen concentration of 5.2 atom % at N-doped MoS2 nanosheets have an excellent catalytic hydrogen evolution reaction, where a low overpotential of 164 mV at a current density of 10 mA cm–2 and a small Tafel slope of 71 dec mV–1–much lower than those of exfoliated MoS2 nanosheets (207 mV, 82 dec mV–1) and bulk MoS2 (602 mV, 198 dec mV–1)–as well as an extraordinary long-term stability of >25 h in 0.5 M H2SO4 can be achieved.

2D Transition Metal Dichalcogenides: Design, Modulation, and Challenges in Electrocatalysis

“…It is considered that both the metal or nonmetal at the edge of TMDs NSs can serve as the catalytic sites, [ 74,82,138,139 ] and the most direct way to enhance the activity involves thinning the layers of TMDs, which could expose the embedded active sites. [ 94,140 ] Liquid exfoliation is a commonly used method to obtain the monolayer, or few‐layer NSs as introduced in Section 3.1. Nguyen et al found the exfoliated MoS 2 NSs had a much larger specific area and the layered structure would expose more active sites, resulting in an Tafel slope of 94.91 mV dec −1 and onset potential of about 100 mV (at 1 mA cm −2 ), whose catalytic activity showed obvious improvement compared to the bulk MoS 2 ( Figure a–c).…”

MoS2 and Perylene Derivative Based Type‐II Heterostructure: Bandgap Engineering and Giant Photoluminescence Enhancement

“…Heterostructure combining 2D transition metal dichalcogenides (TMDs) van der Waals (vdW) materials with organic semiconductors are versatile platform to investigate novel physical and optoelectronic properties toward building multifunctional devices, owing to the unique physics occurring at the TMD‐organic (TMDO) interfaces . Several TMDO heterostructure (HS) exhibit enhanced electrical and optical performances as compared to heterostructures consisting only of organic or inorganic materials . It is worth noting that by manipulating out‐of‐plane surface (i.e., replacing S atom by Se atom) in MoS 2 and other 2D material, such as stanene, can exhibit immense potential for future spintronic system .…”

Apparent Potential Difference Boosting Directional Electron Transfer for Full Solar Spectrum‐Irradiated Catalytic H2 Evolution

“…It is seen H 2 O drop on C 3 N 4 Ts presents a contact angle of 15° compared with 30° on g ‐C 3 N 4 . Therefore, electrons of C 3 N 4 Ts can easily transfer to the adsorbed H 2 O molecules, which will greatly reduce the overpotential of H 2 O splitting, as revealed by the linear sweep voltammetry. In Figure b, the onset potential of H 2 O reduction over g ‐C 3 N 4 , C 3 N 4 Ts, and Ni 2 P/C 3 N 4 Ts‐3 is −0.088, −0.073, and −0.060 V, respectively.…”