The
composites of mesoporous carbon nanospheres with iron oxides
(mPCS@Fe2O3) have been developed for the removal
of antimony in water. The good performance of mPCS@Fe2O3 is attributed to the honeycomblike structure, which is composed
of active Fe2O3 particles dispersedly confined
in the microtunnel of the carbon nanospheres. This adsorbent takes
advantage of the high adsorption capacity and ease of preparation.
It provides a high removal rate for low concentrated Sb(III) and high
removal capacity for high concentrated Sb(III). Furthermore, the used
adsorbent has been developed into a catalyst for the transfer hydrogenation
of nitroarenes, and the catalyst exhibited good activity and inherited
magnetic recyclability. This has proven to be a promising way to avoid
secondary pollution.
Facile and large‐scale preparation of materials with uniform distributions of ultrafine particles for catalysis is a challenging task, and it is even more difficult to obtain catalysts that excel in both the hydrogen evolution reaction (HER) and hydrogenation, which are the corresponding merging and splitting procedures of hydrogen, respectively. Herein, the fabrication of ultrafine bimetallic PtNi nanoparticles embedded in carbon nanosheets (CNS) by means of in situ self‐polymerization and annealing is reported. This bifunctional catalyst shows excellent performance in the hydrogen evolution reaction (HER) and the hydrogenation of p‐nitrophenol. Remarkably PtNi bimetallic catalyst with low metal loading (PtNi2@CNS‐600, 0.074 wt % Pt) exhibited outstanding HER activity with an overpotential as low as 68 mV at a current density of 10 mA cm−2 with a platinum loading of only 0.612 μgPt cm−2 and Tafel slope of 35.27 mV dec−1 in a 0.5 m aqueous solution of H2SO4, which is comparable to that of the 20 % Pt/C catalyst (31 mV dec−1). Moreover, it also shows superior long‐term electrochemical durability for at least 30 h with negligible degradation compared with 20 % Pt/C. In addition, the material with increased loading (mPtNi2@CNS‐600, 2.88 % Pt) showed robust catalytic activity for hydrogenation of p‐nitrophenol at ambient pressure and temperature. The catalytic activity towards hydrogen splitting is a circumstantial evidence that agrees with the Volmer–Tafel reaction path in the HER.
In recent years, the removal of antimony(III) (Sb(III))
contaminant
from water has caused widespread concern. Herein, two adsorbents have
been successfully developed to remove Sb(III) from water and systemically
characterized. One is the composite of magnetic mesoporous carbon
nanospheres (Fe3O4@CNs) with Fe2O3 particles that is represented as Fe3O4@Fe2O3@CNs, and the other one is mesoporous
carbon nanosphere-accommodated Fe2O3 particles
noted as Fe2O3@CNs. Both adsorbents have the
advantages of magnetic separation and high Sb(III) removal capacity.
The adsorption properties of Sb(III) on both adsorbents were studied
by the experiments of adsorption isotherms and kinetics. The results
show that the adsorption behaviors on both adsorbents follow the Langmuir
isotherm model and pseudo-second-order kinetic model. The maximum
Sb(III) adsorption capacity of Fe3O4@Fe2O3@CNs and Fe2O3@CNs is 234.28
and 102.84 mg/g, respectively. The high capacity can be attributed
to the adsorption-active Fe2O3 particles that
are well confined inside the carbon matrix. Furthermore, it is also
of great research value to turn the adsorbed Sb(III) into resources
utilization. We developed the subsequent treatment of the waste adsorbents,
which were manufactured to magnetically recoverable catalysts for
the esterification and 1,2,3-triazoles synthesis, respectively, and
both of them exhibited good catalytic activity. It provides a promising
candidate for avoiding the secondary pollution of Sb(III).
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