Photocatalytic biomass refining offers a promising strategy for the sustainable co-production of high-value chemicals and clean fuels. Herein, a coral-like bifunctional g-C3N4/Mn0.7Cd0.3S S-scheme heterojunction (CNMCS) was rationally constructed for simultaneous xylan photoreforming and hydrogen evolution. X-ray diffraction and transmission electron microscopy analyses confirm the formation of an interconnected hierarchical structure with intimate interfacial contact between g-C3N4 nanotubes and Mn0.7Cd0.3S nanoparticles, while x-ray photoelectron spectroscopy and density functional theory calculations reveal an S-scheme charge transfer pathway driven by the internal electric field. The optimized 6CNMCS photocatalyst achieves a glyceric acid yield of 77.6% and an H2 evolution rate of 2.89 mmol•gcat−1•h−1 without sacrificial agents. The enhanced performance is attributed to efficient charge separation and synergistic interfacial interactions that promote xylan adsorption and selective C–H bond activation. Mechanistic studies indicate that carbon-centered radicals and reactive oxygen species cooperatively drive selective C–C bond cleavage toward glyceric acid formation. This work provides a new strategy for integrating biomass valorization with clean hydrogen production.
We synthesized Bi2WO6 via a hydrothermal approach and subsequently fabricated a Bi2WO6/g-C3N4 heterojunction through grinding process. The resulting composite demonstrated an impressive photocatalytic production rate of hydrogen peroxide at 4809.5 μ mol g-1 h-1, which is nearly double that of CN and 18 times greater than that of BWO. The photocatalytic effectiveness of the BWO/CN composite was thoroughly investigated under different conditions and environmental factors. This enhancement can be primarily attributed to the efficient separation and migration of photogenerated charge carrier pairs facilitated by the S-scheme heterojunction, along with improved redox capability. Photoluminescence spectroscopy and electrochemical impedance spectroscopy (EIS) were utilized to verify the improved efficiency of charge separation. Furthermore, based on X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analyses, in conjunction with band structure calculations, the underlying mechanism of hydrogen peroxide generation and the key factors contributing to the enhanced photocatalytic performance were elucidated.
Zihan Mao, Xuan Ran, Shu Lin et al.· Sultan Qaboos University Jou...· 0 citations
Covalent organic frameworks (COFs) have attracted considerable attention as promising photocatalysts for hydrogen peroxide (H2O2) production. To further improve their catalytic performance, a quaternary ammonium functionality was introduced into the bipyridine units of the COF via a post-synthetic modification strategy. Under identical irradiation conditions, the cationized Pry-COF-QA achieved a H2O2 production rate of 7.31 mmol·h–1·g–1, which is markedly higher than that of the non-protonated Pry-COF (5.50 mmol·h–1·g–1). To gain mechanistic insight into the enhanced activity, density functional theory (DFT) calculations were performed. The results indicate that the incorporation of the quaternary ammonium group fundamentally reconfigures the photophysical behavior. In addition to inducing a red shift in the absorption spectrum by narrowing the HOMO–LUMO energy gap, it more importantly converts the excitation character from a localized excitation (LE) state, which is unfavorable for charge separation, to an intramolecular charge transfer (ICT) state with well-separated spatial distribution. This efficient ICT pathway effectively suppresses electron–hole recombination, thereby significantly prolonging the lifetime of photogenerated charge carriers and ultimately facilitating efficient photocatalytic H2O2 production, while also providing a valuable guideline for the rational design of COF-based systems toward efficient photocatalytic H2O2 generation.
Zhihui Sun, Jiajia Li, Long-Yang Yang et al.· ACS Applied Energy Materials· 0 citations
Revealing the mechanism of photocatalytic organic transformation in aqueous solutions is crucial for photocatalytic processes, yet precisely regulating complex interfacial electron transfer and the microenvironment of reaction molecules remains challenging. Inspired by cellular structures and natural metalloproteins, we construct a ZIF-67@CoS/CdS nanoreactor mimicking organelle architecture. This system enables directional charge transport and hydrogen-bond microenvironment regulation, allowing efficient co-production of H2 and pyruvic acid under light irradiation. Characterizations and calculations reveal that the interfacial electric field accelerates charge migration, while the catalyst reduces the energy barriers for water dissociation and hydrogen formation by modulating hydrogen bonds. The optimized catalyst delivers a molar-level H2 activity of 1457.1 mmol m−2 (5 h, 1,000 cm2) under sunlight, with a pyruvic acid selectivity of 91.2%. In this work, we propose a design strategy for an organelle-mimetic nanoreactor for scalable sunlight-driven H2 production and selective pyruvic acid synthesis. Inspired by cellular structures, this study fabricates an organelle-mimetic nanoreactor to realize the simultaneous co-production of H2 and pyruvic acid via directional charge transport and reaction microenvironment regulation.
Xiao-hong Wang, Xu-jia Liu, Yun-biao Wang et al.· Nature Communications· 0 citations
Covalent organic frameworks (COFs) are promising photocatalysts for solar-driven hydrogen evolution due to their tunable structures and intrinsic porosity. In this work, a series of Tp-Pa-based COFs bearing different electron-withdrawing groups was synthesized via a scalable mechanochemical route to examine the impact of framework functionalization on their structural, electronic, and photocatalytic properties. Spectroscopic analyses (solid-state 1 3C CP-MAS NMR and FT-IR) confirmed the formation of β-ketoenamine linkages, while PXRD revealed higher crystallinity for pristine Tp-Pa compared to its functionalized analogues. Electrochemical studies indicated n-type semiconducting behavior, with pristine Tp-Pa exhibiting more efficient charge separation and lower charge-transfer resistance. Under visible-light irradiation, Tp-Pa showed the highest hydrogen evolution rate (25,717 µmol g- 1 h- 1), whereas functionalized derivatives displayed reduced activity, with Tp-Pa-NO2 being nearly inactive. Notably, Tp-Pa also demonstrated excellent performance in simulated seawater (33,331 µmol g- 1 h- 1). These findings highlight the critical role of functionalization and synthesis strategy in governing crystallinity, charge transport, and photocatalytic efficiency, offering design guidelines for scalable COF-based hydrogen evolution systems.
Kiran Asokan, S. S. Babu· Chemistry - An Asian Journal· 0 citations
The green and efficient synthesis of amino acids is of great importance to both life science and the chemical industry. Electrocatalytic C─N coupling, driven by renewable electricity under mild conditions, offers a sustainable route for converting simple feedstocks into value-added nitrogen-containing compounds and thus provides a promising strategy for glycine production. Bismuth-based catalysts are commonly used in the electrosynthesis of amino acids. Herein, we report a Bi2S3 nanosheet-based catalyst for glycine electrosynthesis under acidic conditions, achieving 67.5% Faradaic efficiency (FE) and a yield rate of 0.51 mmol h-1 cm-2 at 200 mA cm-2. Operando Raman and attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) identify catalyst reconstruction and a tandem mechanism mediated by NH2OH and oxime intermediates. Combined with the control sulfurization experiment on Bi, we found that sulfur incorporation can modulate the product selectivity, possibly by influencing the subsequent hydrogenation of the oxime intermediate to glycine.
The development of stable organic semiconductor photocatalysts-those capable of withstanding harsh conditions while maintaining high activity-remains a significant challenge. To this end, this study proposes an anthraquinone engineering strategy that aims to simultaneously enhance both structural stability and catalytic efficiency of organic semiconductors for photocatalysis. Specifically, 1,3,5-tri(thiophen-2-yl)benzene (TTB)-based porous aromatic frameworks (PAFs) (TTB-PAFs) are optimized by linking anthraquinone fragments via carbon-carbon bond formation. The unique electron distribution, abundant active sites, nanotube-like micromorphology, and robust carbon-carbon bonding character of the optimized TTB-PAF jointly facilitate the charge separation/transfer, mass transportation, and stability during photocatalysis. Remarkably, these result in the optimal C─H cyanation of tertiary amines over the PAF-396 photocatalyst, achieving excellent yields (up to 99%), good substrate adaptability (18 examples), and good recyclability (10 cycles), thereby surpassing the performance of reported porous organic semiconductor materials under similar conditions. Furthermore, PAF-396 also achieves efficient photosynthesis of hydrogen peroxide (H2O2) with a high synthesis rate of 5154 µmol g-1 h-1 from air and water without a sacrificial reagent under blue LED lamp irradiation.
Bingxin Jia, He Wang, Xin Tao et al.· Angewandte Chemie· 0 citations
