Unveiling a Three Phase Mixed Heterojunction via Phase‐Selective Anchoring of Polymer for Efficient Photocatalysis

Abstract

because solar energy is freely available and hydrogen fuel is clean with high gravimetric energy density. For practical applications, it is very important to develop a low-cost water-splitting photocatalyst with an ≈10% solar-to-hydrogen energy conversion. [4] Nearly half of the energy in the sunlight that reaches Earth's surface comes from visible light photons (400-700 nm); therefore, it is important to develop a visible light active photocatalyst for efficient solar-to-fuel conversion. [5] Most of the research on photocatalysts has focused on wide bandgap semiconductors, such as TiO 2 , [6][7][8] SrTiO 3 , [9,10] and carbon nitride (CN). [11][12][13] Some of these photocatalysts have achieved very good operation stabilities that surpass 1000 h, along with more than 50% maximum external quantum efficiency for watersplitting reactions. [14][15][16] However, the wide and difficult-to-tune bandgaps of such photocatalysts restrict light absorption to only the ultraviolet (UV) region and thus fundamentally limit the practical applications for solar light harvesting to fuel. [16,17] Therefore, novel photocatalyst semiconductor materials with narrower bandgaps that can absorb a greater proportion of solar spectrum are needed to achieve the maximum theoretical solar energy conversion efficiency for practical applications.The ligand-to-metal charge transfer (LMCT) facilitated activation of TiO 2 has noteworthy potential for solar energy harvesting. However, the fast back electron transfer from TiO 2 to an oxidized sensitizer is a key limiting factor causing low photocatalyst efficiency. Herein, a new catalyst design to both increase LMCT efficiency and minimize the back electron transfer is presented. A phase-selective modification of mixed-phase TiO 2 (anatase: rutile interface) with poly-salophen organic polymer is developed. The salophen and salen family organic monomers are selectively bound and polymerized on the anatase phase but not the rutile phase, which results in the formation of a three-phase system. Such a three-phase system converts an unfavorable polymer TiO 2 core-shell structure to an intimately mixed blend morphology, consisting of interfaced crystalline rutile TiO 2 and an amorphous polymer-covered anatase-phase TiO 2 . The developed mixed-blend morphology poly-S@P25 can produce H 2 of 37 410 µmol h -1 g -1 of polymer, which is ≈3.4 times higher than core-shell poly-S@anatase TiO 2 . This approach overcomes the drawback of the traditional core-shell structured system for efficient electron harvesting from the LMCT process.

Efficient Nitrate Conversion to Ammonia on f-Block Single-Atom/Metal Oxide Heterostructure via Local Electron-Deficiency Modulation

“…As revealed in Figure 5c and Figure S36a surface, which was quickly reduced or diminished under the applied reduction potential, additionally confirming the wellmaintained structure under the NitRR condition (Figure 5d and Figure S36b). 36,37 Although pure Ni(OH) 2 exhibits a poor NitRR performance (low NH 3 FE and yield rate), the generation of a small amount of in situ formed Ni(OH) 2 under the alkaline media could also enhance the water adsorption and dissociation step, thus supplying necessary protons to the electrophilic single-atom site and indirectly improving the NitRR performance of the Gd SA -D-NiO 400 (Figure S37). 28,38 More importantly, post stability characterizations (XRD, HAADF-STEM, EDS, XPS, and FT-EXAFS) revealed that the structure and electrophilic nature of the Gd SA sites were well maintained after the cycling test, further attesting to their superior chemical stability (Figure S38).…”

Synthesis and Applications of TiO2‐based Nanostructures as Photocatalytic Materials

“…It is easy to recombine, so that the quantum efficiency becomes very low, thereby affecting the photocatalytic efficiency. In order to improve the photocatalytic activity of TiO 2 , a lot of studies have been carried out on the modification of TiO 2 [109–114] . This section briefly introduces metal doping, non‐metal element modification, recombination of TiO 2 with other semiconductors, and multi‐component co‐doping.…”

“…In order to improve the photocatalytic activity of TiO 2 , a lot of studies have been carried out on the modification of TiO 2 . [109][110][111][112][113][114] This section briefly introduces metal doping, non-metal element modification, recombination of TiO 2 with other semiconductors, and multicomponent co-doping.…”

Ion‐in‐Conjugation: A Promising Concept for Multifunctional Organic Semiconductors

“…With the development of sustainable clean‐energy sources, artificial photosynthesis conversion has become promising for transforming solar energy into storable fuel. [ 123 ] Many IIC materials have been studied because of their large molar absorption coefficient from the conjugated structure and strong ion‐involved interactions with reactants. As for type I, the zwitterionic resonance structure could induce the local polarization and separate the charge carriers effectively.…”