Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

Abstract

Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a selfsupporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metalfree hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO 2 spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/ C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.

Deformation Detection Model of High-Rise Building Foundation Pit Support Structure Based on Neural Network and Wireless Communication

“…Whether it is the construction of deep foundations of high-rise buildings or the construction of underground spaces, large-scale underground excavation is inevitable, which is accompanied by a large number of deep foundation pit engineering problems [3]. It is worth noting that the compact construction site and complex surrounding environment of deep foundation pit projects have led to frequent construction safety accidents, causing huge economic losses to the country and society and even casualties, resulting in very bad society influences [4].…”

Graphene-supported metal single-atom catalysts: a concise review

“…In this review, we introduced diverse preparation methods and advantages of graphene-supported metal SACs aimed at solving the above-mentioned challenges. We also summarized their applications in CO oxidation [5, [38][39][40], oxidation of benzene to phenol [41], HER [42,43], methanol oxidation reaction (MOR) [44][45][46], oxygen reduction reaction (ORR) [47][48][49][50], hydrogenation [32,51] and photoelectrocatalysis [52][53][54][55]. At last, we focused on the prospect and future developments of graphene-supported metal SACs.…”

Recent Progress of Hollow Carbon Nanocages: General Design Fundamentals and Diversified Electrochemical Applications

“…at temperature of 500-900 °C, can generate amorphous carbon nanocages. [54,55] However, the SiO 2 -assisted CVD method with gaseous carbon precursor (benzene [56] and methane [57,58] ) at temperature of 1000-1200 °C can generate graphited carbon nanocages. Typically, the carbon shell consists of >10 graphene layers (>5 nm) after 5 min of metal-free CVD growth at 1150 °C, [57] with the graphitization degree comparable to that of multiwall carbon nanotubes.…”