Search

Flower-like BiOI was decorated by CdS nanodots and followed by the introduction of iodine vacancies (V I) for photocatalytic sodium lignosulfonate (SLS) valorization under visible light. The iodine vacancies could adjust the band configuration, strengthen the light absorption and act as electron traps, while the intimate contact between BiOI and CdS nanodots provides a high-speed channel for charge transfer. As a consequence, the photocatalytic performance of SLS conversion into value-added vanillin was greatly improved over CdS/BiOI-V I compared with those of CdS, BiOI and CdS/BiOI. The highest yield of vanillin is 10.95 mg/g SLS over CdS/BiOI-V I , about 5, 8.7, 1.3 times those of CdS, BiOI, CdS/BiOI, respectively, and exceeding most related photocatalysts reported elsewhere. More significantly, as to the lignin from Masson pine and alkali lignin, the corresponding vanillin yield can reach 7.04 and 6.54 mg/g lignin , respectively, under the same condition, which suggests the great potential and universality for photocatalytic lignin valorization over such CdS/BiOI-V I heterostructure. [ABSTRACT FROM AUTHOR]

[Display omitted] Pancake-like TiO 2 (M-TiO 2) derived from the metal-organic framework was inlaid into three-dimensional flower-like BiOI through a facile solvothermal method. M-TiO 2 supplies large surface area and mesoporous structure for attachment and transfer of the substrates and products, while BiOI acts as a photosensitizer to absorb visible light and generates electrons and holes. The distinct structure of M-TiO 2 /BiOI gives a favorable contact between the two monomers, and promotes the transfer of charge carriers. In conjunction with the proper band positions of M-TiO 2 and BiOI, the efficient separation of electron-hole pairs is attained. Benefiting from the above cooperative effects of M-TiO 2 and BiOI, the performance for the vanillin generation from sodium lignosulfonate (SLS) over M-TiO 2 /BiOI composites has a prominent improvement under visible light. Specifically, the yield over optimal M-TiO 2 /BiOI sample is about 5.8 mg/g SLS , obviously superior to that over pristine M-TiO 2 (~1 mg/g SLS) and BiOI (~1.1 mg/g SLS). It is found that h+ and O 2 – play the key role for vanillin generation from sodium lignosulfonate, and the low vanillin generation under UV–vis light sheds light on that OH is an adverse factor. We hoped that this work could inspire the studies on the photocatalytic valorization of biomass using noble metal-free catalysts. [ABSTRACT FROM AUTHOR]

Lignin is abundant and contains a large number of aromatic groups. Herein, Cd x Zn 1-x S photocatalyst with tunable band gap energy was successfully synthesized by using 3-mercaptopropionic acid as a structure tuning additive. Cd x Zn 1-x S can depolymerize alkaline lignin to vanillin by the photocatalytic process. Each gram of alkaline lignin can produce 46.5 mg of vanillin. 2-Phenoxy-1-phenylethanol (PP-ol) and other model compounds were used to understand the depolymerizing process of lignin. Fine tuned Cd x Zn 1-x S can effectively cleave the C β -O-4 bond existed in PP-ol under simulated sunlight. The highest conversion of PP-ol was 89.5% with phenol and acetophenone yields of 66.2% and 33.5%, respectively. The mechanism studies confirm that the C α -H in PP-ol and lignin is firstly dehydrogenated to form C α radical intermediates, and then the photogenerated electrons break the adjacent C β -O bond. This research provides a new strategy to prepare valuable chemicals by virtue of renewable biomass and simulated sunlight. [ABSTRACT FROM AUTHOR]

Mesoporous TiO 2 with regular pancake-like morphology was synthesized by facile calcination of MIL-125 (MIL = Materials of Institut Lavoisier) at different temperatures. The optimal sample MT400 (calcination at 400 °C) is composed of nanoparticles with a size of about 10 nm and mesopores of about 4–12 nm. Its specific surface area can reach up to 174 m2 g−1. In the photocatalytic conversion of sodium lignosulfonate, the yield of vanillin over MT400 is 2.1 mg/g, obviously superior to that over P25 TiO 2 (0.27 mg/g). MT400 with a large specific surface area offers sufficient active sites, and its mesoporous structure provides pathways for the transport of charge carriers and products, giving a satisfactory photocatalytic performance for vanillin generation. It is proved that h+ and ·O 2 − play the key role for vanillin generation from sodium lignosulfonate. This work indicates that MOF-derived metal oxides hold great promise in the application of biomass (photo)catalytic valorization. [Display omitted] • A pancake-like mesoporous TiO 2 was synthesized by the calcination of MIL-125. • MT400 is composed of particles with a size of ca. 10 nm and mesopores of 4–12 nm. • The yield of vanillin over MT400 is 7.7-fold higher than that of P25. • The structure is helpful to the transport of charge carriers, substrates and products. [ABSTRACT FROM AUTHOR]