TiO2 pigments are widely used in paint industries. Inert coating layers were usually deposited on the TiO2 pigments to suppress the photocatalytic activity of TiO2, which can prevent the degradation of surrounding polymer molecules. However, the traditional wet chemical methods normally form thick films, which would impair the pigment properties of TiO2. In this work, SnO2 and SiO2 protective layers were grown on the TiO2 particle surface by low-temperature pulsed chemical vapor deposition. At temperatures <60 °C, thin and uniform amorphous SnO2 films were obtained. The photocatalytic activities of both TiO2/SnO2 and TiO2/SiO2 core–shell particles were suppressed, and TiO2/SnO2 core–shell particles showed higher lightening power than TiO2/SiO2. According to transient fluorescence, photocurrent, and electrochemical impedance spectroscopy measurements, the low electron mobility of amorphous SnO2 and SiO2 films led to fast recombination of photogenerated electrons and holes, thus preventing their migration to the surface and suppressing the photocatalytic activity of TiO2.
Aqueous Zn-ion batteries (AZIBs) are attractive for next-generation renewable and secure energy storage systems due to their high safety and low cost. However, dendrite growth and side reactions of Zn metal anodes severely limit their practical applications. Moreover, polarization is an important but easily overlooked factor hampering the development of AZIBs. Herein, a zincophilic, hydrophilic, and thin (∼100 nm) SnO2 protective layer is reported to remodel the Zn anode/electrolyte interface via a simple spin-coating approach. The SnO2 layer effectively inhibits the growth of the dendrites, which prolongs the lifetime of Zn anodes to 3900 h. It also alleviates the side reactions and endows Zn‖Cu cells with a high Coulombic efficiency of 99.3% over 2000 cycles. Meanwhile, the SnO2 layer presents fast Zn deposition kinetics to ensure reversible Zn anodes at high current/capacity by decreasing electrochemical polarization and concentration polarization. Consequently, SnO2/Zn anodes exhibit a high cumulative capacity of 4.5 A h cm−2 at an ultrahigh current of 30 mA cm−2 with a low overpotential of 90 mV and even 3.2 A h cm−2 at a high capacity of 4 mA h cm−2 and high current of 8 mA cm−2. Prototype SnO2/Zn‖δ-MnO2 full cells also obtain higher capacities and capacity retention (96.9% after 500 cycles at 2C) than bare Zn. This work offers new insights for ensuring the reversibility and durability of Zn anodes with low polarization at high current/capacity and provides a promising way to promote the practical application of AZIBs.
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