A visible-light-Fenton-like reaction system was constructed for the selective conversion of peroxymonosulfate to sulfate radical. Au@CoS, when doped on monoclinic BiVO4{010} facets, promoted spatial charge separation due to the different energy band between the m-BiVO4{010} and {110} facets. The visible-light response of m-BiVO4was enhanced, which was attributed to the SPR effect of Au. And the photogenerated electrons were transferred from the m-BiVO4{010} facet to Au via a Schottky junction. Owing to higher work function, CoS was able to capture these photoelectrons with acceleration of the Co(Ⅱ)/Co(Ⅲ) redox, enhancing peroxymonosulfate conversion to sulfate radical (Co2++ HSO5−→ Co3++ •SO4−+ OH−). On the other hand, holes accumulated on m-BiVO4{110} facets also contributed to organics oxidation. Thus, more than 95% of RhB was degraded within 40 min, and, even after five cycles, over 80% of RhB could be removed. The radical trapping experiments and EPR confirmed that both the sulfate radical and photogenerated hole were the main species for organics degradation. UV-vis DRS, photoluminescence (PL) and photoelectrochemical analyses also confirmed the enhancement of the visible-light response and charge separation. In a pilot scale experiment (PMS = 3 mM, initial TOC = 151 mg/L, reaction time = 4 h), CoS-Au-BiVO4loaded on glass fiber showed a high mineralization rate (>60%) of practical wastewater.
Combining dual-signal channels of differential pulse voltammetry (DPV) and amperometric i–t curve, we developed an amplified sandwich-type electrochemical immunosensor for ultrasensitive detection of prostate specific antigen (PSA). Due to the large specific surface area and good adsorption property, 3-aminopropyltriethox functionalized CeO 2 mesoporous nanoparticles (NH 2 -M-CeO 2 ) was used for supporting toluidine blue (TB) as the electron transfer mediator and anti-PSA as the signal response. To prevent the leak of TB and facilitate the electron transfer property of NH 2 -M-CeO 2 , ionic liquids doped carboxymethyl chitosan (CMC/ILs) were incorporated and TB/M-CeO 2 /CMC/ILs complex was gotten to act as the label of anti-PSA (Ab 2 ). Meanwhile, Au-CoS/graphene was as the matrix materials modifying the electrode to immobilize anti-PSA (Ab 1 ). Specifically, Au-CoS/graphene cannot produce electrochemical signals through DPV method but can provide an obviously electrochemical signal towards catalysis hydrogen peroxide (H 2 O 2 ) through amperometric i–t curve method. At the time of detection, with the increase of concentrations of PSA, the DPV signals from TB/M-CeO 2 /CMC/ILs were increased and the amperometric i–t curve signals from the Au-CoS/graphene were decreased. Under the optimum conditions, the immunosensor demonstrated remarkable analytical performance of a linear range of 0.5 pg/mL to 50 ng/mL with a detection limit of 0.16 pg/mL for quantitative detection of PSA (S/N=3).