Three‐Dimensional Porous Low‐Defect Carbon Nanotube and Graphene Network Supported Rh Nanocrystals as Efficient Methanol Oxidation Electrocatalysts

Abstract

With the rapid economic development and urgent environmental demands, the direct methanol fuel cell (DMFC) as one of environmental‐friendly energy‐conversion systems has attracted wide attention in the world, while the insufficient activity and low structural stability of the anode Pt/carbon catalyst largely deteriorate its overall performance. Herein, we report a facile and cost‐effective bottom‐up method to the fabrication of rhodium nanocrystals supported by three‐dimensional (3D) porous hybrid networks constructed from low‐defect carbon nanotubes and reduced graphene oxide (Rh/LCNT‐RGO) as Pt‐alternative electrocatalysts for DMFC. Such a structural design gives the resultant Rh/LCNT‐RGO hybrid a series of fantastic architectural advantages, such as the large specific surface area of 3D interconnected graphene configuration, high electrical conductivity of low‐defect carbon nanotubes, and abundant catalytically active sites of well‐dispersive Rh nanocrystals. As a consequence, the Rh/LCNT‐RGO hybrid displays unusual catalytic abilities towards the methanol electrooxidation, including a large electrochemically active surface area of 123.8 m2 g−1, a high mass activity of 1228.5 mA mg−1, strong poison tolerance, and long lifespan, far surpassing those of reference Rh/carbon black, Rh/acid‐treated CNT, and Rh/RGO catalysts.

Stereoassembly of ultrasmall Rh-decorated zeolite imidazolate framework–MXene heterostructures for boosted methanol oxidation reaction

“…Remarkably, the largest ECSA value of up to 161.5 m 2 g −1 was achieved for the Rh/ZIF–MX (1 : 1) electrode (Table S1†), followed by Rh/ZIF–MX (3 : 1) (137.8 m 2 g −1 ), Rh/ZIF–MX (1 : 3) (130.1 m 2 g −1 ), Rh/ZIF–MX (5 : 1) (116.4 m 2 g −1 ), and Rh/ZIF–MX (1 : 5) (90.2 m 2 g −1 ). Meanwhile, the Rh/ZIF–MX (1 : 1) electrode also exhibited a remarkably large ECSA value compared with those of conventional Rh/RGO (62.1 m 2 g −1 ), Rh/CNT (41.7 m 2 g −1 ), and Rh/C (39.2 m 2 g −1 ), as well as the recent state-of-the-art Rh-based nanostructures, such as Rh nanosheets, 42,43 Rh nanotubes, 44 Rh nanodendrites, 45 Rh/carbon nanohorns, 46 Rh/CNT–RGO, 47 and Rh/MoS 2 –RGO 48 (Fig. 4b, c and Table S2†), indicating that the newly-designed ZIF/MX matrix with a rational composition was able to expose more Rh active sites than those in previously known materials.…”

Recent progress on 2D material-based nanoarchitectures for small molecule electro-oxidation

“…The Pt/G-CN hybrids exhibit exceptional electrocatalytic capability regarding high electrocatalytic activity, unusually high poison tolerance, and reliable stability due to their superior structure when used as anode electrocatalysts for DMFCs. And such an efficient synthetic approach be extended to the fabrication of 3D nitrogen-enriched, carbon-based nanomaterials with metals or metal oxides, such as Pt/BN-GA, 77 Rh/BN-G, 78 3D LCNT/RGO, 79 3D Rh/G-ZIF, 80 Rh/G-CN, 81 3D Rh/MoS 2 -RGO, 82 3D Pd/MX-RGO. 83 Based on the above discussion, the 3D porous nanoarchitectures made of two-dimensional materials have several obvious merits including: (1) effectively prevents the agglomeration of two-dimensional materials; (2) provides abundant growth sites for the generation of the second component (like noble metal); (3) offers multiscale porous channels for the fast transportation of electrolyte and electrons; (4) maintain the good chemical stability of the catalyst's structure under electrocatalytic progress.…”

Advancements in Noble Metal-Decorated Porous Carbon Nanoarchitectures: Key Catalysts for Direct Liquid Fuel Cells

“…The upper-limit temperature of a liquid phase reaction is the boiling point of the reaction medium. However, the fabrication of high-quality noble metal-decorated porous carbon nanoarchitectures sometimes requires significantly higher synthetic temperatures. , To overcome this obstacle, hydrothermal/solvothermal methods have been utilized to create a high vapor pressure condition and thus raise the upper-limit temperature with the help of a Teflon-lined stainless steel autoclave. − Moreover, the hydrothermal/solvothermal processes could drive the self-assembly of carbonaceous building blocks as well as chemical reduction of metal precursors, which are suitable for the construction of 3D interconnected macroporous or mesoporous carbon networks decorated with diverse noble metal nanocrystals. − …”