Defective Ehanced Subnano-Rh Catalyst Supported on an Ni@Ni-N-C Substrate for Highly Efficient Hydrolytic Dehydrogenation of Ammonia Borane

Abstract

Ammonia borane (NH3BH3, referred to as AB) hydrolytic dehydrogenation is regarded as a feasible strategy for hydrogen production owing to its high hydrogen content, pollution-free nature, and high stability. Metal nitrogen-doped carbon materials (M-N-C) are considered as an ideal candidate support of catalysts with AB hydrolytic dehydrogenation due to the advantages of low cost, large specific surface area, rich defective site, and good chemical stability. In this work, tubular Ni@Ni-N-C was successfully synthesized by high-temperature pyrolysis, and then, Rh nanoparticles were decorated on the support Ni@Ni-N-C by impregnation and reduction to prepare a series of Rh/Ni@Ni-N-C. The best catalytic performance of catalysts is obtained using Ni@Ni-N-C with an Rh loading of 0.74 wt %, showing a turnover frequency as high as 782.18 min–1 and an apparent activation energy (E a) as low as 25.86 kJ mol–1, which could be attributed to the strong interaction between Rh and the defective site of the support.

Enhancing the effect of metal–nitrogen–carbon nanotubes with cobalt phthalocyanine on the electrochemical reduction of CO2

“…1) that the XRD of M–N–C shows an obvious diffraction peak at 44.5° and a weak peak at 25.8°, which could correspond to (100) and (002) planes, indicating the existence of graphitic carbon. 35 Notably, there is no other diffraction peak, speculating that transition metal atoms (Fe, Co, and Ni) may be incorporated into the graphitic carbon with a highly dispersed state. It should be pointed out that both Fe–N–C and CoPc/Fe–N–C had a weak peak at ∼37°, which could be attributed to the presence of trace amounts of Fe 3 C. 36 Obviously, the prepared CoPc/Fe–N–C catalysts should contain Fe–N–C, Fe–N x motif and trace amounts of Fe 3 C. Compared with the support of M–N–C, all CoPc/M–N–C catalysts exhibit two obvious diffraction peaks at 25.8° and 44.5°, and no diffraction peak could be ascribed to CoPc molecules, suggesting that the loading of CoPc molecules is lower than 5% in CoPc/M–N–C catalyst.…”

“…1) that the XRD of M-N-C shows an obvious diffraction peak at 44.51 and a weak peak at 25.81, which could correspond to (100) and (002) planes, indicating the existence of graphitic carbon. 35 Notably, there is no other diffraction peak, speculating that transition metal atoms (Fe, Co, and Ni) may be incorporated into the graphitic carbon with a highly dispersed state. It should be pointed out that both Fe-N-C and CoPc/Fe-N-C had a weak peak at B371, which could be attributed to the presence of trace amounts of Fe 3 C. 36 distributed, which could confirm the high dispersion of CoPc in CoPc/M-N-C. From TEM and HR-TEM images, all CoPc/M-N-C catalysts show similar nanotubes with clean surface morphology (Fig.…”

Recent progress in porous catalysts for dehydrogenation of ammonia borane

“…Compared to metal-free carbon, metal nitrogen-doped carbon materials exhibit superior potential as supporting materials. Liu et al 145 prepared tubular Ni@Ni-N-C via a high-temperature pyrolysis method as a support to load Rh NPs. It is proposed that the defect sites in Rh/Ni@Ni-N-C could be increased by metal nitrogen-doping, and the formation of MN x active centers could facilitate the catalytic reaction rate.…”

Tiny Ni Nanoparticles Embedded in Boron- and Nitrogen-Codoped Porous Carbon Nanowires for High-Efficiency Water Splitting

“…Recently, Ni NPs encapsulated in carbon matrixes, as a new kind of catalysts, have been designed and used as bifunctional HER/OER electrocatalysts. For example, MOF-derived hierarchical Ni@NC hollow microspheres, tubular Ni@Ni–N–C, and onion-like Ni@C-supported carbon nanotubes . These nonprecious metal-based electrocatalysts indeed display advanced HER/OER electrocatalytic activities with good durability.…”