Interface Engineering of an RGO/MoS₂/Pd 2D Heterostructure for Electrocatalytic Overall Water Splitting in Alkaline Medium

Abstract

To achieve sustainable production of H2 at ambient temperature, highly active and stable electrocatalysts are the key to water splitting technology commercialization for hydrogen and oxygen production to replace Pt and IrO2 catalysts. Herein, a modified interface of palladium (Pd) and reduced graphene oxide (RGO)-supported molybdenum disulfide (MoS2) prepared by the solvothermal followed by chemical reduction method is established, in which abundant interfaces are formed. The phase structure, composition, chemical coupling, and morphology of the two-dimensional nanostructures are established by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy, respectively. A structural phase transformation in MoS2 is observed from trigonal (2H) to octahedral (1T) by virtue of Pd addition, which is well established from XRD, Raman, and XPS studies. For oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), the RGO/MoS2/Pd (RMoS2Pd) catalyst exhibits extremely low overpotential (245 mV for OER and 86 mV for HER) to achieve benchmark current density, with small values of Tafel slope (42 mV dec–1 for OER and 35.9 mV dec–1 for HER) and charge transfer resistance. The quantitative study shows the hydrogen production rate of RMoS2Pd of 335 μmol h–1 with excellent stability in alkaline medium, which is superior to MoS2, RMoS2, and MoS2Pd. The improved performance of RMoS2Pd is attributed to the combined synergetic effect of 1T MoS2, sulfur vacancy, and conducting RGO sheet, which efficiently accelerate the overall electrochemical water splitting.

Reutilizing Methane Reforming Spent Catalysts as Efficient Overall Water-Splitting Electrocatalysts

“…The lowest Tafel slopes of MoS 2 @CNF (i.e., 41 mV dec –1 ) and MoS 2 @GC (i.e., 71 mV dec –1 ) as compared to CNF (i.e., 148 mV dec –1 ) and GC (i.e.,195 mV dec –1 ) advocate for the faster kinetics of the fabricated catalysts. The graphitic carbon present on the spent catalyst decreases the interlayer stacking of MoS 2 , resulting in exposed edge sites; furthermore, the transport of charges via the basal plane of MoS 2 is also favored, 62 while in the case of MoS 2 @CNF, the electrocatalytic activity is improved due to the additional surface area of the fibers, providing more vacancy for water to adsorb, dissociate, and release oxygen and showing less affinity toward OH – . 58 The highest exchange current densities revealed by MoS 2 @CNF (i.e., i ° = 2.11 mA cm –2 ) and MoS 2 @GC (i.e., i ° = 1.92 mA cm –2 ) when compared to those of CNF ( i ° = 1.35 mA cm –2 ) and GC ( i ° = 0.385 mA cm –2 ) show that the interfacial barrier for charge transfer is decreased due to which the kinetics of the OER is significantly improved.…”

Strategies to improve electrocatalytic and photocatalytic performance of two-dimensional materials for hydrogen evolution reaction

“…Huang et al [195] used the advantageous vertical growth method to prepare MoS2/CoS2 catalysts. The heterojunction catalyst RGO/MoS2/PD was prepared by Pandey et al [196]; during the heterojunction formation process, a phase transition was observed. The combined effects of the heterojunction interlayer, phase transition, and metal doping resulted in improved HER activity [196].…”

Increasing Electrocatalytic Oxygen Evolution Efficiency through Cobalt‐Induced Intrastructural Enhancement and Electronic Structure Modulation

“…Transition‐metal‐based catalysts (e. g., oxides, phosphides, chalcogenides, and carbonitrides) have attracted tremendous interest in recent years owing to their impressive OER activities, natural abundance, and the consequent low costs [20–22] . Among these, transition‐metal phosphides (TMPs) are considered to be one of the most studied electrocatalytic materials at present [23–25] . However, monometal TMPs usually have poor electroconductivities and inferior stabilities, thus significantly limiting their expected catalytic activities [26–28] .…”

“…[20][21][22] Among these, transition-metal phosphides (TMPs) are considered to be one of the most studied electrocatalytic materials at present. [23][24][25] However, monometal TMPs usually have poor electroconductivities and inferior stabilities, thus significantly limiting their expected catalytic activities. [26][27][28] For this reason, multicomponent TMPs have been developed and have proven to be feasible alternatives for enhancing catalytic performance, both in theory and practice.…”