•The substitution of F− for the host O2− induced the lattice shrinkage•The more positive potential of VB in F-Bi2MoO6 promotes the oxidation power•The oxygen vacancies withdraw the electrons and suppress the recombination of electrons and holes•F-Bi2MoO6 possesses high photocatalytic performance in organic pollutants degradationDevelopment of efficient technologies to deal with organic pollutants in wastewater is an important issue. Photocatalysis, as a “green chemistry” technology, has attracted much attention in pollutants degradation and efficient visible-light-driven photocatalysts with powerful ability to completely oxidize organic pollutants in contaminated source water are highly desirable. Here, a series of fluorinated Bi2MoO6 crystals with different atomic ratio of F to Bi (RF = 0.10, 0.15, 0.20, 0.25, 0.30) were prepared via a solvothermal-calcination process. The effects of F doping on the physicochemical properties of Bi2MoO6 were investigated by physicochemical techniques like XRD, N2 adsorption, SEM, TEM, UV–Vis DRS, FT-IR, XPS, PL and photoelectrochemical measurement. The substitution of F− anions for the host O2− anions induced the lattice shrinkage, a decrease in crystal size and an increase in crystallinity. Moreover, the oxygen vacancies in F-Bi2MoO6 and F− adsorbed over the catalyst surface could withdraw the photoexcited electrons, largely boosting the separation of photoexcited electron–hole pairs. F0.20-Bi2MoO6 displayed significant photocatalytic performance in removal of phenol, bisphenol A, 4-chlorophenol and Rhodamine B dye. ESR and radicals trapping confirmed holes are mainly responsible for the degradation of the target organic pollutants. However, •OH and •O22− could be also involve in photocatalytic reactions. Meanwhile, the more positive potential of VB in F-Bi2MoO6 could promote the oxidation power of the h+ in organic pollutants removal.Fluorinated Bi2MoO6 nanocrystals exhibit efficient photocatalytic removal performance for organic pollutants, e.g. bisphenol A, 4-chlorophenol phenol, and Rhodamine B dye.

Electro-Fenton process for water purification utilizes electrical energy for chemical transformation. However, its key step, oxygen reduction reaction (ORR) to generate H2O2, suffers from added energy consumption due to a side reaction of H2 evolution. This study attempted to make this process energy effective by using an innovative gas diffusion electrode (GDE) fabricated from a carbon material with highly-ordered pores and large surface area (CMK-3). It was found that the employment of this cathode enabled a low cathodic potential of −0.5 V (vs. SCE), at which H2 evolution could be greatly eliminated. Meanwhile, the H2O2 built-up at CMK-3 GDE was 3.1 and 4.4 times higher than those at the other two carbon electrodes (graphite GDE and carbon paper). Moreover, dimethyl phthalate (DMP) degradation in the electro-Fenton process using CMK-3 GDE occurred much more rapidly with a reaction apparent rate constant about 8.8 and 11.5 times higher than those using the other two types of electrodes, respectively, whereas the corresponding energy consumption on CMK-3 GDE at the degradation half-life time was only 50% and 27%, respectively.Highlights► An innovative gas diffusion electrode (GDE) fabricated from a highly-ordered porous CMK-3 carbon. ► A much higher H2O2 built-up rate and dimethyl phthalate (DMP) degradation rate at CMK-3 based GDE. ► An energy-efficient electro-Fenton process with CMK-3 based GDE as the electro-Fenton cathode.

A new concept of desulfurization was developed by designing a series of electrochemical reactions to drive an SO2 absorption-and-conversion process in aqueous solution, hence the SO2 in gas was eventually converted to a valuable chemical of NaHSO4. A model experiment of chemically substantiating this concept includes two steps: (I) absorption of SO2 gas by aqueous solution and oxidation of the absorbed SO2 to SO42− by air and (II) transformation of the SO42− to NaHSO4. The experiment demonstrated that in Step I, the cathodic reduction of O2 from ambient air scavenged the H+ released due to the SO2 absorption and its further oxidation, which thereby were accelerated. Meanwhile H2O2 as a cathodic product further enhanced the SO2 oxidation. In Step II, the anodic oxidation of H2O supplied H+ and allowed the NaHSO4 formation through balances of electrons and mass. Thereafter, a pH range of 5.0−6.0 for the SO2 oxidation was optimized, and an electrochemically driven process for the SO2 conversion to NaHSO4 was proposed. Sustainability evaluation indicated that this concept complies with the principles of green chemistry and potentially enables the SO2 conversion from flue gas to NaHSO4 as a value-added process.