He Junfeng,Hu Jiamin,Mo Xi,Hao Qing,Fan Zhili,He Guannan,Wang Yinzhen,Li Wei,He Qinyu
As photocatalysts exhibit selectivity toward various pollutants, it is necessary to develop different and novel photocatalysts. In this work, a novel photocatalyst-nitrogen-doped simonkolleite Zn 5 (OH) 8 Cl 2 ·H 2 O (DSM) is prepared through a new facile method: calcinating the mixture of zinc hydroxide, urea, and guanidine hydrochloride at 575 °C for 1 h in a furnace with an air atmosphere. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, UV–visble near-infrared diffuse reflection spectra (UV–Vis–NIR DRS), Brunauer–Emmett–Teller (BET) method, Ramen spectra and Zeta potential measurement, photocatalytic properties, as well as active species trapping experiments. XRD and XPS show the as-prepared powder is nitrogen-doped simonkolleite Zn 5 (OH) 8 Cl 2 H 2 O (DSM) with a small ZnCl 2 fraction. SEM investigation indicates that the as-prepared powder possesses a flower-like layered shape. The UV–Vis–NIR exhibits that after doping, the DSM possesses strong light absorption in the ranges of 300–500 and 1400–2500 nm, a direct electronic transition with a band gap energy of 2.469 eV. PL measurement reveals a strong photoluminescence and an up-conversion from lower to higher-energy visible light in as-prepared samples. Zeta potential investigations show that during photocatalysis, the charges on as-prepared photocatalyst are positive. The photocatalytic experiments show a good dark adsorption, a high photodegradation (99.4% at 60 min), a high pseudo-first-order constant ( k ) of 0.0261 min −1 . Meanwhile, the active species trapping experiments suggest that hole (h + ) is the dominant active species during photocatalysis. It is concluded that the doping favors in enhancing vis-light-photocatalysis. This work makes a significant contribution to the literature.
The practical application of aqueous Zn-ion batteries (AZIBs) is hindered by Zn dendrites, hydrogen evolution reaction (HER), and corrosion/passivation of Zn anodes. Herein, a Zn-philic Cu layer is first fabricated on Zn anodes, which not only physically covers scratches and fills defects on Zn anodes but also utilizes the high zincophilicity of Cu to guide uniform Zn deposition. A densely packed Zn 5 (OH) 8 Cl 2 ·H 2 O nanosheets (nZCH) layer is formed on Cu layer, which not only selectively adsorbs H 2 O and repels SO 4 2− to inhibit corrosion/passivation but also prevents electron leakage during Zn deposition in inner Cu layer due to the insulating nature to electrons, thereby suppressing HER. As a result, nZCH-Cu@Zn||nZCH-Cu@Zn symmetric batteries achieve ultra-stable cycling for over 4800 h at 1 mA cm −2 and 3600 h at 5 mA cm −2 . It should be emphasized that both Cu layer and nZCH layer constructed in this paper are obtained through a simple and low-cost one-step in-situ configuration strategy. The three-dimensional structure of nZCH facilitates electrolyte diffusion, ensuring uniform distribution of Zn 2+ concentration and electric field. Moreover, nZCH is a genuine passivation layer with a dense structure. Its presence inhibits the formation of loose pseudo-passivation Zn 4 SO 4 (OH) 6 ·xH 2 O layer, solving the long-standing passivation problem on Zn anodes. The top hydrophilic nZCH layer facilitates Zn 2+ de-solvation, repels SO 4 2− , and adsorbs H 2 O to suppress side reactions, while the bottom Zn-philic Cu layer provides abundant nucleation sites for dendrite-free Zn deposition. Download: Download high-res image (192KB) Download: Download full-size image
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