Edge‐Rich Reduced Graphene Oxide Embedded in Silica‐Based Laminated Ceramic Composites for Efficient and Robust Electrocatalytic Hydrogen Evolution

Abstract

severely restricted their applications. [4] 2D materials, [5] such as metallenes [6] and transition-metal dichalcogenides, [7,8] carbides, [9] and nitrides, [10] have become an irreplaceable choice owing to their large surface area and high electrical conductivity. As the metallic materials suffer from high metal consumption or poor durability, [11] graphene-based metal-free materials, which are earth-abundant resources and have high stability, are potential candidates for electrocatalytic HER. [12] Although perfect graphene is electrochemically inert and often used as a support to load other active nanomaterials, various strategies can be used to adjust its electronic structure and chemical reactivity. [13] For example, the chemical doping of heteroatoms, such as N, S, P, and B, into graphene contributes to high HER activity; [14][15][16][17][18] however, the catalytic mechanism remains controversial. [12] Furthermore, the optimal concentration, proportion, and position of the dopants are difficult to be simultaneously achieved. [19] The topological and edge defects of graphene are important to improve catalytic performance. [20][21][22] Jia et al. first reported a trifunctional graphene catalyst based on the defect mechanism. [23] Due to the abundant structural defects on the edges, the defective graphene exhibited higher electrocatalytic activity than the N-doped graphene. Wei et al. further prepared vertical-oriented N-doped graphene on a glass fiber cloth as a self-support electrode and demonstrated the effects of graphene edge sites on the exceptional HER performance. [24] This method, therefore, is effective in enhancing the HER activity of graphene by creating or exposing more edge sites. Furthermore, more edge sites were exposed in vertical graphene than flat graphene, indicating the importance of graphene orientation. [25] However, the chemical vapor deposition process, commonly used in preparing vertical graphene structures, [26,27] is expensive, complex, and time-consuming. In addition, many graphene-based nanomaterials are in powder form. [28,29] When loading the active materials on the current collector, agglomerations and undesired binders may suppress the electrocatalytic activity and conductivity. [30,31] When the catalysts act as a selfsupported electrode, such as when graphene/ceramic composites are formed, [32] the close contact between the active materials and substrates largely boosts the electrical conductivity To mitigate the energy crisis and environmental pollution, efficient and earth-abundant hydrogen evolution reaction (HER) electrocatalysts are essential for hydrogen production through electrochemical water splitting. Graphene-based materials as metal-free catalysts have attracted significant attention but suffer from insufficient activity and stability. Therefore, a novel and economical approach is developed to prepare highly active, robust, and self-supported reduced graphene oxide (rGO)/SiO 2 ceramic composites as electrocatalysts in HER. Through intercalation and pressure sinteri...

A PdMn bimetallene for low-energy electrocatalytic hydrogen generation coupled with formate oxidation

“…Ecological pollution and energy crisis have stimulated global research on the widespread development of renewable energy. [1][2][3] Hydrogen as a clean, renewable and high-efficiency fuel is a potential candidate for replacing fossil fuels. 4,5 Water electrolysis is regarded as a feasible approach to produce hydrogen in a clean and sustainable manner.…”

Ultra‐wideband electromagnetic interference shielding properties of parallel expanded graphite/Fe3O4 composites

“…In addition, two prominent peaks in Raman spectra (Figure 4A), the G band and 2D band centered at around 1580 and 2700 cm −1 , respectively, confirmed the formation of thin EG sheets. The presence of the D band at around 1350 cm −1 and the high intensity ratio of I D / I G ≈ 1.2 indicated a considerable amount of defective structure in EG 30 . Combined with the XPS results in Figure 4B, these defects might be the residual oxygen functional groups, which could be used as polarization centers 31 in EMI shielding applications.…”

“…The presence of the D band at around 1350 cm −1 and the high intensity ratio of I D /I G ≈ 1.2 indicated a considerable amount of defective structure in EG. 30 Combined with the XPS results in Figure 4B, these defects might be the residual oxygen functional groups, which could be used as polarization centers 31 in EMI shielding applications.…”

Recent advances in precursor-derived ceramics integrated with two-dimensional materials

“…Directional cutting of ceramic composites with parallelly aligned rGO has been shown to result in the formation of a surface with fully exposed rGO edges that can act as active sites in catalytic applications. 122…”