A key auxiliary role of the photothermal effect (PTE) in the enhancement of photocatalytic activity under illumination by near-infrared (NIR) radiation has been experimentally revealed. It was found that the photoexcitation of electrons, required for the process of photocatalysis, does not occur in the presence of NIR radiation alone without the support of both UV and visible radiation. Herein, a binary heterogeneous nanophotocatalyst, GR–ZnO, was fabricated by a novel approach using a hydrothermal process, in which ZnO nanotrapezoids were deposited over the surfaces of graphene nanosheets. In the unique approach reported, the reduction of graphene oxide to graphene has been accomplished using water by an entirely alternative mechanism compared to traditional reduction processes which require hazardous reducing agents. The produced GR–ZnO photocatalyst exhibited excellent performance in the rapid degradation of a perilous dye, methyl orange voluntarily used in industry. It has been found that the PTE is mainly responsible for the rapid degradation of methyl orange, which occurs under NIR laser irradiation. Furthermore, it has been established that the PTE could not emerge with NIR radiation alone, without the support of both UV and visible radiation. Upon considering its importance, the PTE of the GR–ZnO nanocatalyst has been revealed and compared with that of its individual components, viz., graphene and ZnO. Moreover, the photothermal conversion efficiency of the GR–ZnO nanocatalyst was evaluated. Overall, the excellent catalytic activity found in the GR–ZnO nanocatalyst was accounted for by its decreased band gap, which arose because the hybridization of ZnO with graphene could efficiently prevent the recombination of photo-generated charge carriers, resulting in enhanced catalytic activity of GR-ZnO nanocatalyst was attributed to improved optical absorption and enhancement in the adsorption affinity to methyl orange molecules.

An alternative facile approach for the surface modification of naturally available diatoms with xerogel for controlled drug release applications.

Herein, we report the modulation of ZnO for enhancement of its ability toward plasmonic absorption of near-infrared (NIR) photons through coupling of graphene (GR). The reported modification led GR–ZnO to be a promising photocatalyst by the complete removal of poisonous and nonvolatile potassium cyanide from water. The photocatalytic degradation of cyanide was revealed by exposing it to NIR laser and comparing with the rate of UV, visible, and sunlight using their apparent reaction rate constants derived from the Langmuir–Hinshelwood model. The heteronanostructured GR–ZnO promoted rapid photo-oxidation of cyanide under illumination with NIR laser rather than UV, visible, and sunlight. It was assessed that the photothermal effect (PTE) is the main cause for higher catalytic efficiency of GR–ZnO in the presence of NIR radiations. Except for the NIR radiations, GR–ZnO does not show any indication of PTE by irradiating with UV, visible, or sunlight. On account of its significance, the PTE of GR–ZnO in KCN solution was evaluated and compared with its individual components viz., GR and ZnO upon exposure to a 980 nm laser system. Furthermore, it has been revealed that the PTE of GR–ZnO was proportional to its concentration. In addition to its effectiveness in the degradation of cyanide, GR–ZnO retained its special structure and exhibited an outstanding photostability after its repeated use in three successive cycles.

Herein, a promising near-infrared-responsive photothermal agent was designed by anchoring of rice grain-shaped ZnO particles over graphene (GR) nanosheets and subsequent sensitization with cobalt phthalocyanine (CoPc). Thus, produced GR–ZnO–CoPc was able to attain the temperature of 68 °C by irradiating to 980 nm laser for 7 min, which is extremely higher than the endurance temperature of cancer cells. The linear fashioned progression in the photothermal effect of GR nanosheets was conquered by immobilization of ZnO particles and successive sensitization with CoPc. The excellence found in the photothermal effect of GR–ZnO–CoPc was verified by estimation of its photothermal conversion efficiency. The photothermal conversion efficiency assessed for GR–ZnO–CoPc was higher than those for the popular gold- and CuS-based photothermal agents. In addition, it possessed significant stability against photobleaching and structural rupture. It was found that the photothermal effect of GR–ZnO–CoPc is proportional to its concentration. However, by replacement of a 980 nm laser system with 808 nm, the photothermal effect of GR–ZnO–CoPc was reduced, which could be due to lower absorption of GR–ZnO–CoPc at 808 nm compared to 980 nm. On account of its significance and important properties, GR–ZnO–CoPc could be an interesting photothermal agent to employ in future photothermal therapy for cancer.

Article Effect of substrate properties on conductive traces printed with silver-based flexographic ink was published on January 1, 2009 in the journal Nordic Pulp & Paper Research Journal (volume 24, issue 1).