A Three-Dimensional Melamine Sponge Modified with MnOx Mixed Graphitic Carbon Nitride for Photothermal Catalysis of Formaldehyde.

Much attention has been paid to developing effective visible light catalytic technologies for VOC oxidation without requiring extra energy. In this paper, a series of sponge-based catalysts with rich three-dimensional porosity are synthesized by combining MnOx and graphitic carbon nitride (GCN) with commercial melamine sponges (MS) coated with polydopamine (PDA), demonstrating excellent photothermal catalytic performance for formaldehyde (HCHO). The three-dimensional porous framework of MS can provide a good surface for material modification and a reliable interface for gas-solid interaction. The grown layer of PDA framework not only increases the near-infrared wavelength absorption for improving the light-to-heat conversion of catalysts, but also brings excellent adhesion for the subsequent addition of MnOX and GCN. The efficient formaldehyde oxidation is attributed to the sufficient oxygen vacancies generated by co-loaded MnOX and GCN, which is conducive to the activation of more O2- in the oxidation process. As the surface temperature of catalyst rapidly increases to its maximum value at ca. 115 °C under visible light irradiation, the HCHO concentration drops from 160 ppm to 46 ppm within 20 min. The reaction mechanism is certified as a classical Mars-van Krevelen mechanism based on the photo-induced thermal catalysis process.

Solution-based synthesis of wurtzite Cu2ZnSnS4 nanoleaves introduced by α-Cu2S nanocrystals as a catalyst.

Cu2ZnSnS4 is a promising solar absorbing material in solar cells due to its high absorption coefficient and abundance on earth. We have demonstrated that wurtzite Cu2ZnSnS4 nanoleaves could be synthesized through a facile solution-based method. Detailed investigation of the growth process indicates that α-Cu2S nanocrystals are first formed and then serve as a catalyst to introduce the Cu, Zn, and Sn species into the nanoleaf growth for fast ionic conduction. The structure of the as-synthesized nanoleaves is characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, fast Fourier transform, and energy dispersive X-ray spectroscopy mapping. Photoresponses of Cu2ZnSnS4 nanoleaves are evaluated by I-V curves of a Cu2ZnSnS4 nanoleaf film. It is believed that the enhancement of the photoresponse current of the Cu2ZnSnS4 nanoleaf film can be attributed to fast carrier transport due to the single crystalline nature and enhanced light absorption resulting from larger absorption areas of the Cu2ZnSnS4 nanoleaves.