Solution Plasma-Synthesized Black TiO₂ Nanoparticles for Solar–Thermal Water Evaporation

Abstract

Black TiO2 nanoparticles (b-TiO2) with superior solar–thermal water evaporation performance are prepared using a one-step solution plasma process (SPP) in ambient conditions. It is found that radicals that are generated during SPP play a critical role in b-TiO2 formation by comparing several water–alcohol electrolyte environments for the SPP synthesis. Our results show that the radical-induced formation of a black TiO2–x layer on the Ti electrode is necessary for b-TiO2 formation, which was ignored in previous studies. A two-step mechanism for b-TiO2 formation in SPP synthesis is proposed: (I) preoxidation of a Ti electrode surface; and (II) quenching and aggregation of sputtered molten TiO x clusters to form b-TiO2 particles. The b-TiO2-loaded hydrophobic mesh exhibited high water evaporation rates in the solar–thermal water evaporation experiments, which were 1.2, 1.4, and 2.3 times higher than that of the control group without using mesh at 1000, 2000, and 5000 W·m–2, respectively. The understanding in this study may inspire strategies for the facile synthesis of self-structured modified metal-oxide materials for more efficient solar energy harvesting in solar–thermal conversion applications.

Ethanol Solution Plasma Loads Carbon Dots onto 2D HNb3O8 for Enhanced Photocatalysis

“…Optical emission spectroscopy is a non-interference and direct method to study the radicals in the discharge process, which helps understand the liquid plasma discharge process. , In both the discharged water solution and ethanol solution, as shown in Figure e, the excited state of the hydrogen atom at λ = 656.7 nm is detected and corresponds to H α , which confirms the generation of hydrogen radicals in the process of solution plasma discharge. H α has extremely high energy and can attack the HNb 3 O 8 nanosheets in the discharge system, causing hydrogen doping into HNb 3 O 8 . − Considering the lower bond energy in ethanol than in water, ethanol plasma could provide a higher flux of hydrogen radicals, resulting in more significant hydrogen doping. Since the hydrogen dopants are of a shallow energy level, this can reasonably explain the larger upshift of E f of HNb 3 O 8 by ethanol solution plasma.…”

MXene-Based Porous Monoliths

“…Water scarcity is a global issue that drives the development of advanced desalination techniques for water harvesting [ 151 ]. Solar desalination is an effective method for seawater purification by converting solar energy to heat for vapor production [ 152 , 153 ], driving a fast exploration of high solar adsorption materials (such as carbon materials and black TiO 2 ) and advanced architectures (such as hydrogel with many pores structure that can facilitate the water transport) [ 154 , 155 , 156 ]. The optimized combination of the materials, building constructions, and special structures can elevate light-absorbing and photothermal conversion efficiency.…”

Progress on TiO2-based materials for solar water interfacial evaporation

“…Photo-thermal materials with an irregular surface or nanostructure ensure a high evaporation performance (Zhu et al, 2018). In this context, TiO 2 nanocomposites including nanocages (Zhu et al, 2016), nanotubes (Liu et al, 2021), NPs (Zhu et al, 2021), and submicrons (Wang et al, Frontiers in Chemical Engineering frontiersin.org 2021) have been investigated by researchers. TiO 2 NPs were used to fabricate films, membranes, and meshes with mechanical, thermal, and chemical stability under diverse conditions (Li et al, 2017a).…”