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• N-doping creates rich oxygenated groups, defects, and mesopores in Rh/N-U-TiO 2. • The tuning of surface environment induces the generation of electron-rich Rh sites. • The rich active sites with electron-rich features promote H 2 generation from ABH. • Enhanced turnover frequency of 721 min−1 was achieved with Rh/N-U-TiO 2 for ABH. Modulating the surface microenvironment of metal oxide carriers is crucial yet challenging for enhancing the catalytic performance of Rh nanocatalysts in hydrogen production from ammonia borane hydrolysis (ABH). Herein, we developed a nitrogen-modified urchin-like TiO 2 (N-U-TiO 2) supported Rh nanoparticles (NPs) catalyst that demonstrated excellent performance in ABH for hydrogen generation. Characterization results revealed that nitrogen modification introduced abundant oxygenated groups, defects, and mesoporous structure in the carrier, which facilitated the generation of ultra-small and uniformly dispersed Rh nanoparticles, thereby controlling the exposure of active sites on the surface. Moreover, the abundant oxygen vacancies (O v) created through nitrogen modification effectively adjusted the charge distribution and electronic energy levels around the TiO 2 defect sites, promoting electron transfer from N-U-TiO 2 to Rh nanoparticles, resulting in the formation of electron-rich Rh species. These electron-rich Rh species promoted the oxidative cleavage of O H bonds during H 2 O dissociation. Consequently, the Rh/N-U-TiO 2 catalyst exhibited a high turnover frequency of 721 min−1 and good reusability in the ABH reaction, surpassing the performance of Rh/U-TiO 2 and many other reported Rh-based catalysts. This morphology-mediated heteroatom doping approach serves as a valuable guideline for designing metal oxide-supported noble metal catalysts aimed at hydrogen evolution from ABH. [ABSTRACT FROM AUTHOR]

Based on the strong activation activity and affinity of Co and MoS 2 for peroxymonosulfate (PMS), respectively, in this study, a CoS 2 /MoS 2 @chitosan (CoS 2 /MoS 2 @CS) gel with favorable photo responsive behavior was synthetically synthesized for more potent degradation of tetracycline (TC). It was found that CoS 2 /MoS 2 @CS had excellent catalytic active for the degradation of TC under visible light irradiation. The presence of CoS 2 /MoS 2 interfacial structure improve the electron transfer ability of the MoS 2 interface, and the degradation rate of TC was increased from 0.0106 min−1 to 0.0463 min−1, with a high degradation rate of 97.4 %. CoS 2 /MoS 2 can effectively degrade TC within 5 cycles, demonstrating superior cycling stability. In addition, the system degraded different organic pollutants (tetracycline (TC), tetracycline hydrochloride (TCH), crystal violet (CV), and methylene blue (MB)) with a degradation rate higher than 96 %, which supports the ability of the CoS 2 /MoS 2 @CS-PMS system to degrade various chemical contaminants. Quenching analysis indicates that SO 4 •− is the primary reactive chemical free radical for the degradation of TC in the CoS 2 /MoS 2 @CS-PMS system. It provides an approach of combining the synergistic action of Co (II) and photogenerated carriers for more efficient activation of PMS that some inspirations of heterojunction catalysts for AOP applications. • Construction of CoS 2 /MoS 2 heterojunction catalysts as PMS catalysts for TC degradation. • Catalytic activity and cycling stability of TC degradation by CoS 2 /MoS 2 @CS. • Ability of CoS 2 /MoS 2 @CS-PMS system to degrade a variety of organic pollutants. • Synergistic effect of Co(Ⅱ) and photogenerated carriers on TC degradation. [ABSTRACT FROM AUTHOR]

Large‐current‐density electrocatalytic water splitting is essential for industrial hydrogen production, but it is currently hindered by lacking active and robust hydrogen evolution reaction (HER) catalysts. Herein, a novel electrode of hollow nanowire arrays constructed by NiCo modified RuO2 nanoparticles on Ni foam (NiCo@RuO2 HNAs/NF) for high‐performance HER was reported. Such efficient electrode was fabricated by ion exchange with NF‐supported Ni modified cobalt carbonate hydroxide nanowire arrays template (Ni@CoCH NAs/NF). The formed NiCo@RuO2 HNAs/NF only needed overpotentials of 148.5 and 236.1 mV to deliver 500 and 1000 mA cm−2, respectively, along with excellent stability at the high‐current‐density for 300 h. Such remarkable HER performance was mainly attributed to the hollow structure with high surface area, hydrophilic feature, and NiCo@RuO2 with optimized hydrogen evolution kinetics. After coupling with anodic Ni@CoCH NAs/NF, our electrolyzer outperformed Pt/C–IrO2 and most other Ru‐based electrolyzers. This work provides a promising Pt alternative catalyst for profitable H2 production. [ABSTRACT FROM AUTHOR]

Coagulation with aluminum salts is an important method for fluoride removal from groundwater. However, the hydration of aluminum salts generating a large number of H+ usually leads to limited defluorination performance due to the optimum pH of active aluminum phase for fluoride removal around 5.5–6.5. In this work, enhanced fluoride removal from groundwater through precise regulation of active aluminum phase by CaCO3 was investigated. Precipitation products were characterized by XPS, FTIR, XRD, and SEM, respectively, and the mechanism of the high fluoride removal efficiency was discussed and compared with the traditional coagulation of Al2(SO4)3. In the Al2(SO4)3 + CaCO3 (ASCC) system, CaCO3 can stably regulate the pH at the optimum range for active aluminum phase existence and has the best fluoride removal effect. CaCO3 accurately regulated the activity of the aluminum phase by slowly releasing OH− and fine tuning pH, thereby achieving effective fluoride removal. Undissolved CaCO3 particles exist as the carrier of defluorination flocs to accelerate precipitation and improve stability. The work here provides a new method for fluoride removal and may shed light on the application of CaCO3 coagulants for other pollutants. [ABSTRACT FROM AUTHOR]

Cd(II) pollution in water will cause serious threats to the environment and human health. The general remediation protocol for Cd(II) pollution by hydroxide (Ca(OH)2 or NaOH) is still faced with filtering difficulties and high effluent pH. To develop an applicable method for the Cd(II) removal in water, we prepared an activated calcium carbonate (CaCO3) material by changing the crystallinity, particle size, and surface activity of CaCO3, and investigated the corresponding Cd(II) removal capacity from aqueous solutions. The results showed that more than 99.9% of Cd(II) was removed within 10 min in an initial concentration of 50 mg L−1. Moreover, the effluent pH is close to neutral after removal of Cd(II), and the sediment is filtered well. Comparative experiments and characterizations have demonstrated that the excellent Cd(II) removal performance of activated CaCO3 is due to the mechanical activation changes the surface activity of the original stable CaCO3, promotes the slow-release dissolution equilibrium of the active carbonate groups, and thus the coprecipitation of cadmium hydroxide and cadmium carbonate on CaCO3 particles. This research demonstrates that mechanical activation of CaCO3 could be used as a repair material for efficient removal of heavy metal pollution in water, which can solve the problems of filtration and high effluent pH of alkaline precipitation. [ABSTRACT FROM AUTHOR]