Nanospatial Charge Modulation of Monodispersed Polymeric Microsphere Photocatalysts for Exceptional Hydrogen Peroxide Production

Abstract

However, the current global industrialized anthraquinone (AQ) oxidation is known as an inefficient method of producing H 2 O 2 due to its multi-step reaction process, utilization of noble metal catalysts, high energy input, severe pollution, etc. [8,9] Therefore, the development of sustainable methods with the requirements of low-cost, safe, and environmentally friendly for producing H 2 O 2 is highly sought after, such as using renewable solar energy. [10] Photocatalysis has attracted increasing attention as it converts earth-abundant resources into valuable chemicals by utilizing renewable solar energy. [11] Compared to the traditional AQ method, the photocatalytic H 2 O 2 production process requires only a solar energy supply and a photocatalyst, which makes it a promising method to produce H 2 O 2 . [12] Significant efforts have been focused on the boosting light-driven H 2 O 2 production performance by employing inorganic-based semiconductor photocatalysts. [13][14][15] However, these inorganics are mostly inefficient due to their four-electron reduction of O 2 (O 2 + 4H + + 4e − → 2H 2 O) and the decomposition of the formed H 2 O 2 by disproportionation or photoreaction. [16] Polymer based photocatalysts could be considered as an alternative candidate, especially polymeric graphitic carbon nitride (g-C 3 N 4 ). [17,18] However, g-C 3 N 4 is restricted by its intrinsic low efficiency, which stems from insufficient visible-light harvesting and poor charge separation. In the last decade, various strategies, including doping with heteroatoms, [19] engineering defects, [20] morphology control, [21,22] loading metal nanoparticles, [23] singleatom modification [24] and nanocomposites, [16,10] have emerged to enhance the hydrogen peroxide production activity of g-C 3 N 4 with a maximum solar-to-chemical conversion (SCC) value of 0.67% achieved. [25] In a recent study, procyanidins, 4-methoxybenzaldehyde and carbon dots were condensed into a metalfree photocatalyst by using a phenolic condensation approach, which can produce H 2 O 2 with 0.21% SCC efficiency in seawater. [26] Therefore, a polymeric photocatalyst with wide light absorption and efficient charge separation is necessary.So far, the understanding of the catalytic mechanism of polymeric photocatalysis has yet to reach the level of metal oxide Photocatalysis offers a sustainable strategy for hydrogen peroxide (H 2 O 2 ) production, which is an essential oxidant and emerging energy carrier in modern chemical industry. The development of polymer-based photocatalysts to produce H 2 O 2 has great potential but is limited by lower efficiency due to the limitation of light utilization and the low charge separation efficiency. Herein, a series of monodispersed mesoporous resorcinol-formaldehyde resin spheres (MRFS) are reported with a rational designed spatial charge distribution, exhibiting wide light absorption with a solar-to-chemical conversion (SCC) efficiency of 1.1%. Surface photovoltage microscopy (SPVM) measurements unraveled the charge separation in nan...

Versatile synthesis of dendritic mesoporous rare earth–based nanoparticles

“…(23)(24)(25). However, the composition of the obtained dendritic mesoporous nanoparticles is limited to SiO 2 , dopamine, resorcinol formaldehyde, Au, Pd, Pt, and Al 2 O 3 (26)(27)(28)(29)(30)(31)(32). The mesostructure of the reported porous rare earth-based materials is disordered, and its structural parameters are difficult to be regulated (33,34).…”

Molecularly Engineered Covalent Organic Frameworks for Hydrogen Peroxide Photosynthesis

“…Different from the XRD characteristic peak of AP-TfpBpy, the strong XRD peak of COF at 2θ = 3.68°c orresponded to the (100) plane, indicating that the COF material has a better crystalline morphology (Figure S1a). Further characterization data of IR, 13 C NMR and XPS confirmed the same chemical composition and bond structure of AP-TfpBpy and COF-TfpBpy, respectively (Figure S1b-d, Figure S2). SEM and TEM images showed that the crystals of COF-TfpBpy and AP-TfpBpy are both interlaced linear morphology, and COF-TfpBpy has better crystallinity (Figure S3).…”

“…At 333 K, the AQY@420 nm and SCC efficiency of COF-TfpBpy were 13.6 % and 1.08 %, respectively, which were higher than the most efficient photocatalyst RF/P3HT (AQY, 10 %; SCC efficiency, 1.0 %; Figure 1g and Table S1). [13] To the best of our knowledge, COF-TfpBpy is the first COFs catalyst reported that can photocatalytically produce H 2 O 2 without the presence of sacrificial reagents or stabilizers. [5d] At present, the reported concentrations of H 2 O 2 photocatalytically produced after 8 h (the average time of light in a day) are at the mM level, which can be used directly for environmental remediation.…”

“…In order to determine which monomer is the active site in COF-TfpBpy (Figure 3a), the bipyridine monomer was replaced by benzidine (Bd), 2,6-diaminoanthraquinone (Daaq) or p-phenylenediamine (Pa) to form COF-TfpBd (Figure 3b), COF-TfpDaaq (Figure 3c) and COF-TfpPa (Figure 3d), respectively. The structure, chemical bond, morphology, specific surface area and light absorption capacity of the prepared COF-TfpBd, COF-TfpDaaq and COF-TfpPa were determined by PXRD, IR, 13 C NMR, XPS, SEM, TEM and BET (Figure S15-S25), and the suitable band structures for photocatalytic H 2 O 2 production by the above three COFs were determined by DRS and Mott-Schottky plots. Finally, the performance of these materials on H 2 O 2 photocatalytic synthesis was studied.…”

“…[12] The SCC efficiency of the same catalyst at 333 K (1.08 %) was also higher than the highest value to date (1.0 %, no sacrifice reagents and buffer reagents). [13] After 8 h of irradiation (the average duration of light in a day), the concentration of synthesized H 2 O 2 reached 5.6 mM, which was directly used to degrade Rhodamine B (RhB) and inactivate Escherichia coli (E. coli). More importantly, we revealed the importance of bipyridine in COFs for H 2 O 2 photocatalytic production from water and air.…”