Three-Dimensional Zn_0.5Cd_0.5S/Reduced Graphene Oxide Hybrid Aerogel: Facile Synthesis and the Visible-Light-Driven Photocatalytic Property for Reduction of Cr(VI) in Water

Abstract

A series of three-dimensional ZnxCd1-xS/reduced graphene oxide (ZnxCd1-xS/RGO) hybrid aerogels was successfully synthesized based on a one-pot hydrothermal approach, which were subsequently used as visible-light-driven photocatalysts for photoreduction of Cr(VI) in water. Over 95% of Cr(VI) was photoreduced by Zn0.5Cd0.5S/RGO aerogel material within 140 min, and such photocatalytic performance was superior to that of other ZnxCd1-xS/RGO aerogel materials (x≠0.5) and bare Zn0.5Cd0.5S. It was assumed that the enhanced photocatalytic activity of Zn0.5Cd0.5S/RGO aerogel was attributed to its high specific surface area and the preferable synergetic catalytic effect between Zn0.5Cd0.5S and RGO. Besides, Zn0.5Cd0.5S/RGO aerogel materials were robust and durable enough so that they could be reused several times with merely limited loss of photocatalytic activity. The chemical composition, phase, structure, and morphology of Zn0.5Cd0.5S/RGO aerogel material were carefully examined by a number of techniques like XRD, SEM, TEM, BET, Raman characterizations, and so on. It was found that Zn0.5Cd0.5S/RGO aerogel possessed hierarchically porous architecture with the specific surface area as high as 260.8 m2 g−1. The Zn0.5Cd0.5S component incorporated in Zn0.5Cd0.5S/RGO aerogel existed in the form of solid solution nanoparticles, which were uniformly distributed in the RGO matrix.

Surface Modification of Commercial Cotton Yarn as Electrode for Construction of Flexible Fiber-Shaped Supercapacitor

“…It is well known that RGO has a typical peak at~24 • and there is indeed a wide and weak XRD peak at 23.5 • for the purchased RGO powder (red curve) [24,25]. However, such a peak is absent in the XRD pattern of cotton-RGO-AgNP fiber and therefore it is likely that it is overlapped by the dominant peak originating from the cotton constituent [25,26].…”

“…In addition, five more sharp diffraction peaks appear at 38.2 • , 44.3 • , 64.5 • , 77.5 • and 81.5 • in this pattern, perfectly coinciding with the XRD peaks of elemental silver nanoparticles (blue curve), which belong to the crystallographic planes of (111), ( 200), ( 220), (311) and (222) for face-centered cubic silver (JCPDS: 65-2871), respectively [23,24]. It is well known that RGO has a typical peak at~24 • and there is indeed a wide and weak XRD peak at 23.5 • for the purchased RGO powder (red curve) [24,25]. However, such a peak is absent in the XRD pattern of cotton-RGO-AgNP fiber and therefore it is likely that it is overlapped by the dominant peak originating from the cotton constituent [25,26].…”

A State-of-the-Art of Metal-Organic Frameworks for Chromium Photoreduction vs. Photocatalytic Water Remediation

“…It is important to note that the performance of r-GO is lower than GO due to the intense transition to the semi-metal state of r-GO and low density of the π electron in its surface [ 76 ]. On the other hand, hybrid materials synthesized from GO and different semiconductors such as bismuth [ 77 , 78 , 79 ], metal oxides (ZnO [ 80 , 81 , 82 ], TiO 2 [ 83 , 84 , 85 , 86 , 87 ], WO 3 [ 88 , 89 ], g-Fe 3 O 4 [ 90 ]) carbon nitride [ 91 ], quantum dots [ 92 , 93 ], metal sulphide [ 94 , 95 , 96 , 97 , 98 ], silver chromate [ 99 ], and metallophthalocyanines [ 100 , 101 ] have shown even better photocatalytic efficiency to chromium reduction in comparison with the pristine GO. The aforementioned behavior is attributed to the excellent conductivity of graphene which allows a quick and easy movement of the photogenerated electrons between hybrid materials, avoiding the recombination and consequently favoring the chromium reduction.…”