Abstract
A novel type of bi-functional microencapsulated phase change material (MEPCM) microcapsules with thermal energy storage (TES) and carbon dioxide (CO2) photoreduction was designed and fabricated. The polyaniline (PANI)/titanium dioxide (TiO2)/PCN-222(Fe) hybrid shell encloses phase change material (PCM) paraffin by the facile and environment-friendly Pickering emulsion polymerization, in which TiO2 and PCN-222(Fe) nanoparticles (NPs) were used as Pickering stabilizer. Furthermore, a ternary heterojunction of PANI/(TiO2)/PCN-222(Fe) was constructed due to the tight contact of the three components on the hybrid shell. The results indicate that the maximum enthalpy of MEPCMs is 174.7 J·g−1 with encapsulation efficiency of 77.2%, and the thermal properties, chemical composition, and morphological structure were well maintained after 500 high–low temperature cycles test. Besides, the MEPCM was employed to reduce CO2 into carbon monoxide (CO) and methane (CH4) under natural light irradiation. The CO evolution rate reached up to 45.16 μmol g−1 h−1 because of the suitable band gap and efficient charge migration efficiency, which is 5.4, 11, and 62 times higher than pure PCN-222(Fe), PANI, and TiO2, respectively. Moreover, the CO evolution rate decayed inapparently after five CO2 photoreduction cycles. The as-prepared bi-functional MEPCM as the temperature regulating building materials and air purification medium will stimulate a potential application.
Highlights
In our previous work [29], a kind of microencapsulated phase change material (MEPCM) with TiO2 /PDVB hybrid shell was fabricated by Pickering emulsion polymerization; the use efficiency of single functional TiO2 NPs in the MEPCM is relatively low, nonfunctional PDVB shell could not achieve a synergetic combination of NPs and shell for further improving the multi-functionality especially the photocatalysis
The amount of TiO2 and PCN-222(Fe) NPs embedded on the surface of the MEPCM decreased with the continuous increase of the amount of PANI, resulting in the poor dispersion and aggregation of MEPCMs
paraffin@PANI/TiO2 /PCN-222(Fe) (PPTP)-3 MEPCM has an ideal dispersion (Figure 1e), where more NPs are accumulated on the surface
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In our previous work [29], a kind of MEPCM with TiO2 /PDVB hybrid shell was fabricated by Pickering emulsion polymerization; the use efficiency of single functional TiO2 NPs in the MEPCM is relatively low, nonfunctional PDVB shell could not achieve a synergetic combination of NPs and shell for further improving the multi-functionality especially the photocatalysis. A novel bi-functional MEPCMs consisting of a paraffin core and a PCN222(Fe)/titanium dioxide/polyaniline hybrid shell was prepared for solar photocatalysis and thermal storage. A green Pickering emulsion polymerization was used for microencapsulating PCM with PANI/TiO2 /PCN-222(Fe) hybrid shell, where. The fabricated paraffin@PANI/TiO2 /PCN-222(Fe) (PPTP) MEPCMs can absorb solar energy for heat storage, but the heterojunction hybrid shell can achieve efficient separation of hole-electron pairs to improve the photocatalysis of CO2 into CO and CH4. Illustration of the fabrication of paraffin@PANI/TiO2 /PCN-222(Fe) MEPCMs by Pickering emulsion polymerization
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