An In Situ Polymerization‐Encapsulation Approach to Prepare TiO₂–Graphite Carbon–Au Photocatalysts for Efficient Photocatalysis

Abstract

A complex nanoarchitecture composed of TiO2 nanobelts, graphite‐like carbon, and Au nanoparticles (NPs) is developed using an in situ surface polymeric encapsulation technique. The precise arrangement of the carbon layer and Au NPs on a TiO2 surface can be programmed to form three different core@shell structures by simply varying the addition sequence of materials during the encapsulation process. The photocatalytic activity of the three nanoarchitectures is assessed in H2 generation, degradation of dye molecules as well as photoelectrochemical cells under solar and visible light irradiation. In the reaction of H2 generation, no activity can be detected for all samples under visible‐light, while under solar light the sample with Au on the surface of carbon layers wrapped on TiO2 shows the highest activity. By stark contrast, in the photodegradation test, significant difference in activity under visible light is observed, where the sample with Au NPs sandwiched between carbon layers demonstrates the highest activity. All the results indicate that the synergistic effect of carbon‐layers and Au NPs is essential for the catalytic activity enhancement. Moreover, the activity of the photocatalysts is not only highly dependent on the architecture of the catalyst, but also on the type of reaction investigated.

A Microorganism Bred TiO2/Au/TiO2 Heterostructure for Whispering Gallery Mode Resonance Assisted Plasmonic Photocatalysis

“…The architectural distribution as the key substance of the E- TiO 2 /Au/TiO 2 heterostructure was further verified by element mapping (Figure h), which indicates that the Au NPs are covered by TiO 2 (the region is indicated in Figure S5), due to their presence on the E. coli surface prior to TiO 2 growth. HR-TEM imaging (Figure i) further shows details of the TiO 2 /Au/TiO 2 heterostructure, in which the lattice fringes with a spacing of 2.35 and 3.52 Å correspond to the (111) planes of Au and (101) planes of anatase TiO 2 , respectively. , …”

“…HR-TEM imaging (Figure 1i) further shows details of the TiO 2 /Au/ TiO 2 heterostructure, in which the lattice fringes with a spacing of 2.35 and 3.52 Å correspond to the (111) planes of Au and (101) planes of anatase TiO 2 , respectively. 20,42 The structure of E-TiO 2 /Au/TiO 2 was analyzed using X-ray diffraction (XRD) spectroscopy. Figure 2a shows the XRD patterns of the E-TiO 2 /Au/TiO 2 (upper, blue curve) and E. coli-like TiO 2 (E-TiO 2 ) (lower, black curve).…”

“…Loading Au nanoparticles (NPs) on a semiconductor surface to form hybrid structures (e.g., TiO 2 /Au nanohybrid) has been proven to be an effective approach to improve the visible photon absorption as well as energetic charge carrier transfer for photocatalysis, due to the SPR of Au NPs. − Within this configuration, visible light is absorbed by the plasmonic NPs with an enhancement of local electric field at the TiO 2 –Au interface. , The SPR absorption and the high field enhancement at the TiO 2 –Au interface favor the generation of “hot” electrons in metal NPs, as well as their injection into the conduction band of conjugated TiO 2 for photocatalysis. , To achieve better visible light responses, Au NPs with various sizes or shapes have been coupled with TiO 2 nanostructures, as the SPR band of the plasmonic NPs can be readily modulated by their morphologies . Nonetheless, challenges still exist in the synthesis and structural design to obtain plasmonic nanohybrids with greatly enhanced absorption and near field properties. ,− For instance, great efforts have been merely focused on tuning the SPR of metal NPs to enhance absorption in photocatalysis; − however, the use of resonances within the large band gap dielectrics has been only recently explored in detail.…”

Architecture Dictates the Activity of Hollow TiO2 Nanospheres in Photocatalytic Solar Energy Conversion

“…Extensive research into morphology engineering, notably via the tuning of shape and size, − cocatalyst deposition, − and the exposure of high-energy facets , has resulted in the development of highly active photocatalysts. Such intricate morphologies can provide increased surface areas and more active sites, leading to enhanced photocatalytic activities.…”

Ultrasonic-Assisted Synthesis, Characterization, and Photocatalytic Application of SiO2@TiO2 Core-Shell Nanocomposite Particles

“…Despite the favorable properties of TiO 2 in the decomposition of dyes, it is not thermally stable when applied independently as a powder form and tends to dissolve with losing its surface area in the solution. It is also known that when TiO 2 nanoparticle is used as free-suspending systems in photocatalysis, it shows better efficiency and photocatalytic activity compared to the encapsulated ones [15][16][17]. However, there are a number of disadvantages of using free-suspending systems such as loss of catalyst, instability of the catalyst particles, and difficulties for the separation of the particles after treatment.…”