Dingliang Dai,Jianhao Qiu,Guanglu Xia,Lu Zhang,Hong Ma,Luan Yang,Jianfeng Yao
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.
In this paper, controllable nucleation and growth of CdS nanodots on the (020)-featured WO 3 ·H 2 O nanoplates has been successfully accomplished to prepare CdS-WO 3 ·H 2 O heterojunction with high-quality interfacial contact through a slow release of Cd 2+ and S 2- from the gradual self-loop hydrolysis of cadmium acetate and thioacetamide. The chemical and structural characteristics of as-prepared samples before and after heat treatment are detailedly investigated by TG-DSC, XRD, Raman, XPS, FESEM and HRTEM, as well as their light absorption performance from UV-Vis DRS. The maximum average hydrogen production rate for CdS-WO 3 ·H 2 O reaches 2.15 mmol·g −1 ·h −1 under 300 W Xe lamp irradiation (λ > 420 nm) using lactic acid as sacrificial reagent, which is 8.27 and 2.72 times as much as CdS and CdS-WO 3 , respectively. According to band alignment, CdS-WO 3 ·H 2 O exhibits greater energy difference of Fermi level than CdS-WO 3 , and augmented photocatalytic performance should arise from efficient Z-scheme charge transfer mechanism under stronger built-in electric field, in which the conduction band electrons of WO 3 ·H 2 O and valence band holes of CdS are expected to effectively recombine at their interfacial zones, while the conduction band electrons of CdS and valence band holes of WO 3 ·H 2 O contribute to the reduction of H + and oxidation of lactic acid.