Effective Catalytic Reduction of 4-Nitrophenol to 4-Aminophenol over Etched Halloysite Nanotubes@α-Ni(OH)₂

Abstract

A series of supported α-Ni(OH) 2 structures on etched halloysite nanotubes (eHAs) are synthesized via a one-pot facile co-precipitation method. By expediently controlling the variety of alkali source, etched halloysite nanotubes@α-Ni(OH) 2 (eHA@α-Ni(OH) 2 ) with different α-Ni(OH) 2 morphologies and Ni 2+ -ion contents can be achieved. The prepared eHA@α-Ni(OH) 2 is used to catalytically reduce 4-nitrophenol (4-NP). It shows that eHA@α-Ni(OH) 2 prepared with n-butylamine as an alkali source (eHA@α-Ni(OH) 2 -B) exhibits a higher k app of 1.458 × 10 −2 s −1 and K of 583.27 s −1 •g −1 . The catalytic reduction property is in accordance with the Ni 2+ -ion content of eHA@α-Ni(OH) 2 . Moreover, it also exhibits a good cycle stability due to the synergy of the support eHA and the supported Ni 2+ ions in α-Ni(OH) 2 , which can achieve a 99% 4-nitrophenol conversion after 11 cycles. The Ni 2+ -ion reduction experiment illustrates that the Ni 2+ ion is the activation site and the enhanced 4-NP reduction activity of eHA@α-Ni(OH) 2 -B is attributed to the higher Ni 2+ -ion content, which accelerates the electron transport from NaBH 4 to 4-NP to result in the catalytic reduction of 4-NP to 4-aminophenol (4-AP).

Rationally designed transition metal hydroxide nanosheet arrays on graphene for artificial CO2 reduction

“…Two peaks at low angles (<20°) clearly indicate the layered structure of Ni (OH) 2 32 . Notably, the positions of (003) and (006) diffraction peaks shift towards lower angle as compared to that of standard card, indicating enlarged interlayer spacing of as-obtained Ni (OH) 2 , which has been widely reported in the previous literatures 32,36,37 . In addition, Ni(OH) 2 -GR hybrids exhibit analogous XRD patterns to that of the blank Ni(OH) 2 .…”

Manipulation of the halloysite clay nanotube lumen for environmental remediation: a review

“…Probably for the convenience of preparation, metallic NPs are usually supported on the outer wall of halloysite nanotubes. 31,32,35 However, such exposed catalysts generally exhibit the following disadvantages: mechanical wear during use can easily cause the abscission of metallic NPs, thereby shortening the service life of the catalyst; moreover, small metallic NPs are prone to agglomerate or sinter at elevated temperatures, thereby reducing their catalytic activity.…”

“…[21][22][23][24][25][26][27][28][29][30] These reviews mainly focus on the excellent support function of the outer wall of clay nanotubes, which is related to its elongated nanorod (NR)-like shape. For example, various metallic NPs such as Cu, ZnO, α-Ni(OH) 2 , Co 3 O 4 and CeO 2 -WO 3 , [31][32][33][34][35][36] or functional organic molecules such as cucurbiturils, chitosan, polyaniline, hydrothermal carbon, organosilane and dopamine, [37][38][39][40][41][42] were supported on the outer wall of clay nanotubes to prepare advanced hybrid nanomaterials, and then used as high-…”

A study on the high efficiency reduction of p-nitrophenol (4-NP) by a Fe(OH)3/Fe2O3@Au composite catalyst

“…[43][44][45] The development of efficient methods for reducing nitro groups to amino groups using new catalysts has attracted great attention in synthetic organic chemistry. [46][47][48][49] In the eld of catalysis, the reduction of 4-NP to 4-AP has been widely used as a benchmark system for evaluating the catalytic ability of metal-based materials. 50 The reaction was carried out in an aqueous solution at room temperature to evaluate the catalytic capacity of prepared Fe(OH) 3 /Fe 2 O 3 @Au.…”