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2 jour nal o f e nvironmental sciences 92 (2020) 1 e10

gas shift reaction, and hydrogenation reactions (Bai et al., other creatures due to its toxicity and difficulty in degradation.
2014; Cui et al., 2015; Chen et al., 2017; Wu et al., 2017). The While, its reduction product, p-aminophenol (PAP), can be
metal-support interaction, especially the strong metal- involved in various fields including drugs, developing agent,
support interaction, can induce the phenomenon that elec- polymers, agrochemicals, pigments, and dyes. So it is of great
tron transfer from support to metal, and thus the geometric or importance to realize the conversion of PNP to PAP (Tafesh and
electronic property of catalysts can be significantly altered, Weiguny, 1996; Shi et al., 2010; Li et al., 2012, 2015; Qiao et al.,
which shows a substantial influence on catalytic activity and 2017; Karki et al., 2018). The hydrogenation reduction of PNP by
stability (Yuan et al., 2018). Surface facets, surface polariza- NaBH 4 is thermodynamically feasible only with the aid of
tion, oxygen vacancy and so on have been identified as valid appropriate catalysts (Khalavka et al., 2009; Zhang et al., 2012;
strategies to modify electronic structures of materials, which Huang et al., 2012b; Antonels and Meijboom, 2013; Fu et al.,
are attributed to the efficiency of interfacial interaction (Sun 2013; Johnson et al., 2013; Kalekar et al., 2013; Liao et al., 2016).
et al., 2010; Huang et al., 2012a; Bao et al., 2015). Numerous reports focus on the synthesis and the activity of
The support in the synthesized heterogeneous catalysts various catalysts, but the catalytic properties for the reduction of
plays a significant role to catalytic activity because of its in- PNPbyAg/Fe 2 O 3 with specific morphology were rarely reported.
ternal properties such as morphology, components, oxygen Herein, we prepared three different Ag/Fe 2 O 3 composites
vacancy, and so on (Schubert et al., 2001; Li et al., 2013). The with different support morphologies including nanoplates
mechanism about the interfacial interaction between metal (NPs), nanospheres (NSs), and nanocubes (NCs). The reduction
and the support, especially the reducible oxides, for example, of PNP with excessive reductant under ambient condition was
TiO 2 , CeO 2 ,Fe 2 O 3 , have been widely investigated (Ou et al., chosen to evaluate the catalytic activity. The catalytic activ-
2011; Liu et al., 2012; Yuan et al., 2018). Zhao et al. (2016) re- ities of three catalysts showed obvious. Diverse measure-
ported a novel composite catalyst with different crystal facets ments were carried out to investigate the morphology
used as supports for selective catalytic reduction of NO with dependence of the hematite support. The high performance of
NH 3 , and discovered that the TiO 2 nanosheets supported Ag/Fe 2 O 3 NPs could be attributed to the strong electron
catalyst showed much better activity, stability and durability interaction between Ag and plate-like Fe 2 O 3 at their interface.
than the TiO 2 nanoparticles supported catalyst. Larsen et al.
(2016) investigated the catalytic performance of Au deco-
rated Fe 2 O 3 catalyst with different shapes, including spheres, 1. Materials and methods
rings, and tubes, using a similar methods, which confirmed
that the supports with specific morphology determined the 1.1. Materials and reagents
catalytic performance. To demonstrate the effect of metal-
support interaction, the CO oxidation was catalyzed by Pt/ Allreagentswereofanalyticalgrade andusedwithout further
FeO x catalyst obtained via using a co-precipitation method, in purification. Iron chloride hexahydrate (FeCl 3 $6H 2 O), Fe 2 O 3
which its high performance was attributed to the synergetic nanospheres (Fe 2 O 3 NSs), sodium acetate, sodium oleate, oleic
effect of surface FeO x and Pt (Xu et al., 2018). Recently, Chen et acid, ethanol, sodium borohydride, silver nitrate, p-nitrophenol
al. (2020) reported that three kinds of Au nanoparticles with were purchased from Sinopharm Group Chemical Reagent Co.
different morphologies, including Au nanospheres (Au-NSs), Ltd., China. Deionized water (18 MU,cm) from a Millipore Q
Au nanorods (Au-NRs) and Au nanopentogons (Au-NPs), were water purification system was used throughout the
prepared and used as photosensitizers to modify TiO 2 hollow experiments.
nanoboxes to enhance the photocatalytic activity, which
ascribe the best performance to the surface plasma resonance 1.2. Preparation of Fe 2 O 3 nanocrystals
(SPR) effect of Au-NRs.
The reduction potential of Ag decreases due to the Fe 2 O 3 NPs and NCs were prepared with different hydrother-
increased Fermi potential, which makes it possible to be uni- mal and solvothermal methods as previously reported (Wang
versally applied in the electron transfer process (Saha et al., et al., 2007; Chen et al., 2010).
2010). The state of Ag, including the geometric or electronic For the preparation of Fe 2 O 3 NPs, 1.09 g of FeCl 3 $6H 2 O was
properties, may be altered due to the effect of the support or added to the mixed solution consist of 40.0 mL ethanol and
the metal-support interaction. For Ag/CeO 2 catalysts with 2.8 mL deionized water. And then 3.2 g of sodium acetate was
various morphologies including nanorods, nanoparticles, and added to the mixture with magnetic stirring until completely
nanocubes, the catalytic activities primarily relayed on the dissolved. After that, the mixture was transferred into a
morphologies of the support, which was on account of the 100 mL Teflon-lined stainless steel autoclave, and heated at

surface oxygen vacancy concentration produced by the 180 C for 12 hr. The red precipitate was collected, and washed
interfacial interaction between Ag and CeO 2 with different thoroughly by deionized water, and ethanol, respectively.
morphologies (Yu et al., 2018). When Ag/MnO 2 catalysts with Finally, the obtained product was dried at 40 C for 12 hr.

different morphologies (wire-like, rod-like and tube-like) were Fe 2 O 3 NCs were synthesized by a reported solvothermal
used for the toluene oxidation, it was demonstrated that the method. In brief, 5.33 g sodium oleate, 27 mL of ethanol, 4.3 mL
morphology of the support significantly affected the state of of oleic acid, and 23 mL of water were mixed together, and then
Ag and the metal-support interaction, thus determining the 1.6 g of FeCl 3 $6H 2 O was added to the solution. After stirring for
activity (Li et al., 2016). 2 hr, the mixture was transferred into a 100 mL Teflon-lined

p-Nitrophenol (PNP), one of the common organic pollution stainless steel autoclave, and heated at 180 C for 12 hr. Until
existing in the wastewater, can cause damage to human and cooling to ambient temperature, the product was collected,