Search

The presence of phenol in coal-chemical engineering wastewater is considered a serious environmental issue. The use of enzymes to degrade phenol has received wide attention. G-quadruplex can combine with hemin to form G-quadruplex/hemin, which shows peroxidase-like activity and can be used to degrade phenol. In this work, a novel CNTs-NH2@G-quadruplex/hemin was designed using a single-stranded DNA (ssDNA) that contained G-rich fragments and T-rich fragments. The G-rich fragments assembled with the hemin to form G-quadruplex/hemin; the pyrimidine group of the T-rich fragment could form stable chemical bonds with the amino group, which could be used for immobilization. Characterization analysis of FTIR, XRD and TEM showed that the CNTs-NH2@G-quadruplex/hemin was successfully prepared. Meanwhile, the activity and phenol degradation ability for CNTs-NH2@G-quadruplex/hemin were studied in detail, and the effects of pH, temperature, initial phenol concentration, H2O2 concentration and reusability on the degradation efficiency of phenol were also explored. The results showed that when immobilized, the CNTs-NH2@G-quadruplex/hemin presented good activity, especially under conditions of temperature 30 °C and pH 7.0. Notably, the maximum reaction velocity of CNTs-NH2@G-quadruplex/hemin was increased from 0.016 mM mg−1 min−1 (free enzyme) to 0.056 mM mg−1 min−1. For phenol degradation ability, it was observed that under the conditions of temperature 30 °C, pH 7.0, initial phenol concentration 40 mg L−1, H2O2 concentration 120 mM, enzyme dose 40 mg L−1, more than 90% of phenol could be degraded within 600 min. In addition, the CNTs-NH2@G-quadruplex/hemin still maintained high activity after 10 cycles of phenol removal, demonstrating its appealing potential for practical applications. [ABSTRACT FROM AUTHOR]

The catastrophic dendrite hyperplasia and parasitic reactions severely impede the future deployment of aqueous Zn‐ion batteries. Controlling zinc orientation growth is considered to be an effective method to overcome the aforementioned concerns, especially for regulating the (002) plane of deposited Zn. Unfortunately, Zn (002) texture is difficult to obtain stable cycling under high deposition capacity resulting from its large lattice distortion and nonuniform distribution in electric field. Herein, different from traditional cognition, a crystallization orientation regulation tactic is proposed to boost Zn (101) texture exposure and inhibit zinc dendrite proliferation during plating/stripping. Experimental results and theoretical calculations demonstrate the malate molecules preferentially adsorb on the Zn (002) facet, leading to the texture exposure of distinctive Zn (101) plane. Meanwhile, the −COOH and −OH groups of malate molecules exhibit strong adsorption on the Zn anode surface and chelate with Zn2+, achieving H2O‐poor electrical double layer. Very impressively, the multifunctional malate additive enlists zinc anode to survive for 600 h under a harsh condition of 15 mA cm−2/15 mAh cm−2. Moreover, the symmetric cell harvests highly‐reversible cycling life of 6600 h at 5 mA cm−2/1.25 mAh cm−2, remarkably outperforming the ZnSO4 electrolyte. The assembled Zn//MnO2 full cells also demonstrate prominent electrochemical reversibility. [ABSTRACT FROM AUTHOR]

The difference of NH 3 oxidation mechanism over SAPO-34 and Cu-SAPO-34 was studied. XRD (X-ray diffraction), SEM (scanning electron microscopy) and H 2 -TPR (H 2 -temperature programmed desorption) were conducted to estimate the Cu species distribution. The quantity of individual Cu 2+ ions escalated with the elevation of silicon content in the Cu/SAPO-34 catalysts, leading to an enhancement in the activity of the NH 3 -SCR (ammonia-selective catalytic reduction) process. This augmentation in activity can be attributed to the increased presence of isolated Cu 2+ species, which are pivotal in facilitating the catalytic reaction. In addition, the kinetic test of NH 3 oxidation indicated that the CuO species were the active sites for NH 3 oxidation. Specifically, the strong structural Brønsted acid sites were the NH 3 oxidation active sites over the SAPO-34 support, and the NH 3 reacted with the O 2 on the Brønsted acid sites to produce the NO mainly. While the NH 3 oxidation mechanism over Cu/SAPO-34 consisted of two steps: firstly, NH 3 reacted with O 2 on CuO sites or residual Brønsted acid sites to form NO as the product; subsequently, the generated NO was reduced by NH 3 into N 2 on isolated Cu 2+ sites. Simultaneously, the isolated Cu 2+ sites might demonstrate a significant function in the NH 3 oxidation process to form N 2 . The identification of active sites and corresponding mechanism could deepen the understanding of excellent performance of NH 3 -SCR over the Cu/SAPO-34 catalyst at high temperature., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)