Ultrafine Pt Nanoparticles and Amorphous Nickel Supported on 3D Mesoporous Carbon Derived from Cu-Metal–Organic Framework for Efficient Methanol Oxidation and Nitrophenol Reduction

Abstract

The development of novel strategy to produce new porous carbon materials is extremely important because these materials have wide applications in energy storage/conversion, mixture separation, and catalysis. Herein, for the first time, a novel 3D carbon substrate with hierarchical pores derived from commercially available Cu-MOF (metal-organic framework) (HKUST-1) through carbonization and chemical etching has been employed as the catalysts' support. Highly dispersed Pt nanoparticles and amorphous nickel were evenly dispersed on the surface or embedded within carbon matrix. The corresponding optimal composite catalyst exhibits a high mass-specific peak current of 1195 mA mg Pt and excellent poison resistance capacity ( I/ I = 1.58) for methanol oxidation compared to commercial Pt/C (20%). Moreover, both composite catalysts manifest outstanding properties in the reduction of nitrophenol and demonstrate diverse selectivities for 2/3/4-nitrophenol, which can be attributed to different integrated forms between active species and carbon matrix. This attractive route offers broad prospects for the usage of a large number of available MOFs in fabricating functional carbon materials as well as highly active carbon-based electrocatalysts and heterogeneous organic catalysts.

Unusual Effect of Trace Water on the Structure and Activity of NixCo1−x Electrocatalysts for the Methanol Oxidation Reaction

“…The red curve in Figure a shows that the catalytic activity of the Ni 0.6 Co 0.4 alloy (116 mA cm −2 ) is clearly better than those of single nickel and cobalt metals (black and blue curves) and indicates a good synergistic effect between Ni and Co with appropriate ratio. The Ni atoms tend to lengthen the C−O bond length in the methanol molecule, which also can be easily absorbed by NiOOH mainly because of its empty d orbital or unpaired electrons . Although cobalt does not have the effect of oxidizing methanol (blue curve in Figure a), it still plays an important role in Ni x Co 1− x .…”

“…The Ni atoms tend to lengthent he CÀOb ond length in the methanol molecule,w hich also can be easily absorbedb yN iOOH mainly because of its empty do rbitalo ru npaired electrons. [57] Although cobalt does not have the effect of oxidizing methanol (blue curve in Figure 5a), it still plays an important role in Ni x Co 1Àx .F irst, the conductivity of Co(OH) 2 in solution is better than that of Ni(OH) 2 ,w hich is beneficialt o electron transport. [64] Additionally, absorption of CO and the intermediate products on cobalt can greatly facilitate their furthero xidation by Ni 3 + and decrease the CO poisoningo f Ni.…”

“…More importantly,h igher I f /I b means that methanola nd intermediate products (including CO) adsorbed on the catalyst surface can be more easily converted to CO 2 during the anodic sweep. [7,56,57] Although the polyhedral Ni-Co structure with a size of 100-150 nm synthesized by the classical method also has ac atalytic effect on methanol oxidation ( Figure S11), its oxidationp eak current density is only approximately 20 mA cm À2 , which provest hat small particles with rough surface can ChemSusChem 2020, 13,964 -973 www.chemsuschem.org efficiently increaset he specific surface area and the resulting electrocatalytic activity for the MOR.…”

Rational Localization of Metal Nanoparticles in Yolk–Shell MOFs for Enhancing Catalytic Performance in Selective Hydrogenation of Cinnamaldehyde

“…The similar structure of pristine Ni/Zn‐MOF (Figures S4 and S5) suggests that the encapsulation of Pt NPs did not damage the structure of Ni/Zn‐MOF, in agreement with the PXRD result. Importantly, the yolk–shell structure of the MOF and a clear cavity between the outer shell and inner yolk sphere were further revealed by TEM (Figure D), in which the Pt NPs with exposed (111) plane are uniformly distributed (Figure S6) . Furthermore, the energy‐dispersive X‐ray spectroscopy (EDS) mapping analysis of Pt void @MOF(Y) showed that the Zn, Ni, and Pt elements in Pt void @MOF(Y) are homogeneously distributed on the Echinoidea‐like structure (Figure E).…”

“…Importantly,t he yolk-shell structureo ft he MOF and ac lear cavity between the outer shell and inner yolk sphere were furtherr evealed by TEM ( Figure 1D), in which the Pt NPs with exposed (111)p lane are uniformly distributed (Figure S6). [10] Furthermore, the energy-dispersive X-ray spectroscopy (EDS) mapping analysis of Pt void @MOF(Y) showed that the Zn, Ni, and Pt elements in Pt void @MOF(Y) are homogeneously distributed on the Echinoidea-like structure ( Figure 1E). Thus, the spatial distribution of incorporated Pt NPs in/on the MOF can be controlled by their addition sequence.…”