The surface modification of Ag3PO4 using anionic platinum complexes for enhanced visible-light photocatalytic activity
Graphical abstract
Introduction
Utilizing platinum as a dopant has been widely used to improve the catalytic activity of photocatalyst. Many types of platinum can be incorporated into photocatalyst. The most common type is the metallic Pt nanoparticles, as utilized for TiO2 photocatalyst modifications [1], [2]. Other types are platinum ion, complex-ion, and cluster ion. The Pt ions doping into the lattice of TiO2 is supported by the similar ionic radii of Pt4+and Ti4+ [3]. The combination of Pt2+ ion and metallic Pt can also be applied to enhance catalytic activity of α-Fe2O3 [4]. The Pt2+ in α-Fe2O3 increases the isolation efficiency of the photo-induced carriers that improve the lifespan of hole carriers, whereas the metallic Pt in α-Fe2O3 brought to the generation of Schottky barriers. TiO2 surface modification using the clusters ion of [Pt3(CO)6]62− also improves the catalytic activity [5]. Platinum clusters act as charge scavenger that inhibits charge recombination and also act as a sensitizer.
Herein, the anionic platinum complexes doping in Ag3PO4 was successfully synthesized. Anionic platinum complexes successfully substitute the phosphate ion of Ag3PO4 under sonication. The substitution effectively occurs on the silver vacancy of Ag3PO4. Up to now, there is no report of incorporating the Ag3PO4 by platinum complexes, and the result is very significant for the improvement of Ag3PO4-based photocatalyst. The rate of catalytic increased up to 5.8 times higher compared to the pure Ag3PO4. The RhB can be degraded to 99.36% for only 6 min under the blue LED irradiation of 3 W.
Section snippets
Experimental
The Ag3PO4 and defect-Ag3PO4 were prepared using the co-precipitation method based on the previous results [6]. To prepare the defect-Ag3PO4, the starting material of AgNO3 (0.85 g) and Na2HPO4·12H2O (1.79 g) were dissolved in 200 mL of ethanol–water (50% ethanol) and 50 mL of water, respectively. The Na2HPO4 aqueous solution was slowly added to AgNO3 ethanol-aqueous solution. The precipitates in this reaction were filtered and washed with distilled water and subsequently dried in an oven at
Results and discussion
Fig. 1 shows the XRD pattern of Ag3PO4 (AP), defect-Ag3PO4 (DAP), Ag3PO4/ PtCl62-(AP/Pt) and defect-Ag3PO4/PtCl62- (DAP/Pt). All of the samples exhibited a structure of body-centered-cubic (JCPDS No.06-0505) [8]. A little shift and doublet of the XRD pattern might be due to the effect of PtCl62− incorporation.
The absorption of samples is presented in Fig. 2, and the bandgap energies were determined by the following formula (1):where A, h, v, and Eg were absorbance, Planck constant,
Conclusion
Anionic platinum complexes successfully substitute the phosphate ion of Ag3PO4. The anionic platinum complexes incorporation in Ag3PO4 significantly improved the catalytic activity of Ag3PO4. The excellent photocatalytic activity was ascribed to efficient electron transfer between the Ag3PO4 conduction band and the chemically bonding of platinum complexes brought to efficient charge separation.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This research was supported by the Ministry of Research, Technology and Higher Education of the Republic of Indonesia in the Scheme of Basic Research, 176/SP2H/LT/DRPM/2019. It was also partly supported by the JSPS KAKENHI Grant Number JP16H06439 and the Cooperative Research Program of “Network Joint Research Center for Materials and Devices”
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