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Active co-catalysts have been extensively used for improving photocatalytic activity in semiconductor-based photocatalytic systems. Herein, 2D alkalized Ti3C2 (Ti3C2-OH) nano-sheets were coupled with CdS via a facile electrostatic self-assembly strategy and combined with hydrothermal method to prepare Ti3C2-OH/CdS photocatalyst. The morphologies, crystal phases, optical and photoelectrical properties of the prepared photocatalysts were characterized by XRD, SEM, TEM, FTIR, PL, and EIS analysis, respectively. The photocatalytic degradation results verified that the photo-degradation performance of Ti3C2-OH/CdS photocatalyst (degradation of 97% RhB in 100 min) was obviously superior to that of pure CdS (degradation of 70% RhB in 100 min) and Ti3C2/CdS (degradation of 82% RhB in 100 min). The active species trapping experiments for Ti3C2-OH/CdS photocatalyst revealed that the superoxide radical (·O2−) and holes (h+) were the predominant species for degradation of RhB. Furthermore, the Ti3C2-OH co-catalyst in the Ti3C2-OH/CdS composite not only played the role of promoting the effective separation of photo-generated electron–hole pairs, but also constructing strong connections with CdS semiconductor to establish heterostructure, ultimately enhancing the photocatalytic performance of the Ti3C2-OH/CdS photocatalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zn x Cd 1-x S was firstly applied to photo-Fenton system as catalyst and co-catalyst. • The ZCS-3 photo-Fenton system exhibited satisfactory catalytic performance. • The photocatalysis of that system was synergized with co-catalysis. The exploration of new catalysts or co-catalysts to promoting the circulation efficiency between Fe3+ and Fe2+ in photo-Fenton system is of great significance for sewage treatment. Herein, metallic sulfides (Zn x Cd 1-x S) with different molar ratio of Zn/Cd were constructed by a facile solvothermal technology and applied to photo-Fenton system as both catalyst and co-catalyst for the first time. The catalytic activity of photo-Fenton systems could be enhanced by adding any as-prepared samples. Moreover, photo-Fenton system containing ZCS-3 (molar ratio of Zn:Cd = 3:7) presented the highest degradation rate for Rhodamine B (RhB, 93.5%), which showed significant improvement compared with that of photo-system without ZCS-3(43.7%). The excellent performance of this photo-Fenton system was mainly ascribed to the synergistic effect between photocatalytic and co-catalytic of ZCS-3. EPR and XPS results confirmed that the Zn2+ in the ZCS-3 would be reduced to Zn+ by the •O2–, which generated under visible light irradiation in photo-Fenton system. Thereby, more Zn+/Zn2+ exposed on the ZCS-3 surface during this photo-Fenton reaction, ensuring the acceleration of conversion between Fe2+ and Fe3+. The catalytic mechanism revealed that the formation of stable double recycles of Zn2+/Zn+ and Fe2+/Fe3+ in catalytic process displayed prominent enhancement for the catalytic properties of the photo-Fenton system. [ABSTRACT FROM AUTHOR]

Novel plasmonic photocatalysts have been extensively investigated because of their advantages in efficient light absorption and surface plasmon resonance effect (SPR). Herein, plasmon-induced BiPO 4 /Ag/Ag 3 VO 4 heterostructures were constructed by in-situ partially reduction along with hydrothermal approach. Photo-degradation results revealed that BiPO 4 /Ag/Ag 3 VO 4 -1.2 (abbreviation as Bi/Ag-1.2) product presented a significant enhancement of photoactivity for Methyl orange-MO, Congo red-CR and tetracycline-TC degradation under visible light irradiation, which was higher than that of pristine BiPO 4 and Ag/Ag 3 VO 4 , respectively. Moreover, this excellent performance of Bi/Ag-1.2 was mainly ascribed to the synergistic effect consisting of intimate heterostructure between BiPO 4 and Ag/Ag 3 VO 4 and SPR effect of Ag, thus ensuring an accelerated separation and transfer of photo-generated carriers and promoting the absorbance of visible light. The trapping test and electron spin resonance further demonstrated that h+ and ·O 2− species are the vital active species in the photocatalytic reaction. Meanwhile, a plausible photocatalytic mechanism induced by plasmon-based heterojunctions was systematically proposed. [ABSTRACT FROM AUTHOR]

• The novel Yb3+/Tm3+ co-doped Ti 3 C 2 /Ag@Ag 3 VO 4 composite was fabricated by in-situ partially reduction-hydrothermal strategy. • The resultant Yb3+/Tm3+ co-doped Ti 3 C 2 /Ag@Ag 3 VO 4 composite exhibited enhanced photo-degradation performance under visible light irradiation. • The synthetic process and the corresponding photocatalytic mechanism was proposed and investigated detailedly. A novel Yb3+/Tm3+ co-doped Ti 3 C 2 /Ag/Ag 3 VO 4 composite with stable and robust photodegradation performance was synthesized by in-situ partially reduction along with hydrothermal strategy. In the composite, block-like Ag 3 VO 4 particles are self-assembled on the surface of 2D Ti 3 C 2 MXene accompanied by partial reduction of Ag+ to Ag0. Photodegradation results showed that the resulting Yb3+/Tm3+ co-doped Ti 3 C 2 /Ag/Ag 3 VO 4 composite with optimal Yb/Tm proportion (Y/T:0.3/0.005) presented a boosting photocatalytic performance for degradation of tetracycline (TC) and organic dyes under visible light irradiation. The removal efficiency was 97% for TC in 20 min, 96% for rhodamine B in 25 min, and 99% for methylene blue in 20 min, which was higher than that of Ag/Ag 3 VO 4 composite. As manifested by photoelectrochemical measurements, the enhanced photocatalytic performance of the Y/T:0.3/0.005 composite was attributed to the improved light absorption and excellent charge separation induced by the formation of intermediate energy states after co-doping Yb3+/Tm3+ ions. Meanwhile, the photocatalytic mechanism of the photocatalyst was also investigated through electron spin resonance (ESR) spectra and trapping experiments, which verified that the active species of h+ and ·O 2 − play the important role for photodegradation of tetracyline and organic dyes. [ABSTRACT FROM AUTHOR]

Ternary Ti 3 C 2 –OH/ln 2 S 3 /CdS composites with an efficient visible-light-driven photocatalytic performance have been prepared via a facile hydrothermal synthesis method. The photo-degradation experiments verified that Ti 3 C 2 –OH/ln 2 S 3 /CdS composite with a large surface area of 68.2 m2/g exhibited an enhanced photocatalytic activity and adsorption capacity towards Rhodamine B under visible light irradiation, which was higher than that of the naked CdS and ln 2 S 3 , respectively. Furthermore, Ti 3 C 2 –OH/ln 2 S 3 /CdS composite showed robust degradation efficiency for mixture dyes of RhB and Methyl Orange (MO), and its catalytic ability was superior to that of ternary GO/ln 2 S 3 /CdS composite. The trapping experiments for active species revealed that hole (h+) and •O 2 − species played a critical role in the removal of organic pollutants. In summary, the enhanced photocatalytic performance of Ti 3 C 2 –OH/ln 2 S 3 /CdS photocatalyst was derived from an excellent charge carrier separation and transfer of Ti 3 C 2 –OH MXene and the synergistic effect between CdS and ln 2 S 3 which resulting in strong visible light response. Image 1 • The Ti 3 C 2 –OH/In 2 S 3 /CdS composite was fabricated via a facile hydrothermal route. • The Ti 3 C 2 –OH/In 2 S 3 /CdS composite exhibited enhanced photo-degradation performance under visible light irradiation. • The photocatalytic mechanism of the Ti 3 C 2 –OH/In 2 S 3 /CdS composite has been investigated carefully. [ABSTRACT FROM AUTHOR]