Dual‐Functional Photocatalysis for Cooperative Hydrogen Evolution and Benzylamine Oxidation Coupling over Sandwiched‐Like Pd@TiO₂@ZnIn₂S₄ Nanobox

Abstract

attention owing to its clean and high energy density property. [2c,d,3a,4] To facilitate the photocatalytic activity, most of the photocatalytic systems were conducted by adding various SEDs, namely triethylamine, monoethanolamine, diethanolamine, triethanolamine (TEOA), methanol, ethanol, L-ascorbic acid, ethylenediamine, tetraacetic acid, and phenol. These SEDs are believed to eliminate the photoinduced holes and in return promote the photoinduced electrons for hydrogen generation. [5] The introduction of hazardous organic scavengers for photoinduced holes not only enhances the cost of the photocatalytic reaction, but also brings extra pollution or wastes. Therefore, extensive endeavors should be devoted to the overall water splitting process without any organic sacrificial reagents. Although great progress has been made for overall water splitting, [6] their quantum efficiency is far lower than industrial application. It is more interesting to develop dual-functional photocatalysts for hydrogen evolution on one side and make full use of SEDs consumption or oxygen evolution for organic oxidation on the other side. [7,8] It is a very meaningful procedure to oxidative couple the amines to form imines, which possesses multiple applications as one of the biologically active nitrogencontaining organic compounds. Therefore, combining the PHE Photocatalytic hydrogen evolution (PHE) over semiconductor photocatalysts is usually constrained by the limited light-harvesting and separation of photogenerated electron-hole pairs. Most of the reported systems focusing on PHE are facilitated by consuming the photoinduced holes with organic sacrificial electron donors (SEDs). The introduction of the SEDs not only causes the environmental problem, but also increases the cost of the reaction. Herein, a dual-functional photocatalyst is developed with the morphology of sandwichedlike hollowed Pd@TiO 2 @ZnIn 2 S 4 nanobox, which is synthesized by choosing microporous zeolites with sub-nanometer-sized Pd nanoparticles (Pd NPs) embedded as the sacrificial templates. The ternary Pd@TiO 2 @ZnIn 2 S 4 photocatalyst exhibits a superior PHE rate (5.35 mmol g −1 h −1 ) and benzylamine oxidation conversion rate (>99%) simultaneously without adding any other SEDs. The PHE performance is superior to the reported composites of TiO 2 and ZnIn 2 S 4 , which is attributed to the elevated light capture ability induced by the hollow structure, and the enhanced charge separation efficiency facilitated by the ultrasmall sized Pd NPs. The unique design presented here holds great potential for other highly efficient cooperative dual-functional photocatalytic reactions.

Hollow Nanoboxes Cu2‐xS@ZnIn2S4 Core‐Shell S‐Scheme Heterojunction with Broad‐Spectrum Response and Enhanced Photothermal‐Photocatalytic Performance

“…The photothermal effect is important for improving photocatalytic activity. [ 13 ] An IR camera was used to observe variations in the photocatalyst's surface temperature as a function of irradiation time. The temperature fluctuations of the three materials were observed from 0 to 120 s under simulated sunlight exposure.…”

“…[ 27,45 ] 2) The photothermal system is improved thanks to the composites’ low band gap. [ 13,41 ] 3) Because the composite material absorbs more light, the absorption of NIR light increases as well. [ 13 ]…”

“…[ 13,41 ] 3) Because the composite material absorbs more light, the absorption of NIR light increases as well. [ 13 ]…”

“…[27,45] 2) The photothermal system is improved thanks to the composites' low band gap. [13,41] 3) Because the composite material absorbs more light, the absorption of NIR light increases as well. [13] Figure 4a shows the photocatalytic hydrogen generation performance of five photocatalysts: Cu 2-x S, ZnIn 2 S 4 , 12%-Cu 2-x S@ZnIn 2 S 4 , Cu 2-x S@ZnIn 2 S 4 , Cu 2-x S@ZnIn 2 S 4 , and 36%-Cu 2-x S@ZnIn 2 S 4 .…”

“…[11] Metal sulfides are key research hotspots among photocatalysts and have been widely exploited in many photocatalytic processes. [12][13][14] ZnIn 2 S 4 is a ternary metal-sulfide semiconductor that has been extensively studied by scientists due to its appropriate band gap (2.34-2.48 eV), excellent redox potential, and chemical stability for the reaction. [15][16][17] However, due to its inefficient photogenerated charge separation and low transferability, poor photoreduction ability, and low activity due to the quick complexation of photogenerated electrons and holes, the single ZnIn 2 S 4 still limits its use in photocatalysis.…”