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Biochar as a multi-functional material has been widely used in the fields of catalysis and pollutant removal, but its feasibility to enhance biologic nitrobenzene reduction with the mixed culture and the long-term impact on nitrobenzene removal and microbial structure are lack of a clear clarification. This study aimed at evaluating the feasibility of biochar to enhance anaerobic reduction of nitrobenzene with a mixed culture. We initially investigated the effect of the biochar addition on nitrobenzene removal in short-term experiments and then possible enhancement mechanisms for the biochar were explored. Additionally, the impacts of different key parameters on biological nitrobenzene reduction were studied in the presence of biochar. Moreover, the long-term influence of the biochar on biological nitrobenzene removal with the mixed culture was also evaluated. The results showed that the estimated pseudo first-order rate constant of nitrobenzene removal in the presence of 1.0 g L −1 biochar was four times higher than that without biochar addition. The possible enhancement mechanisms may be owing to that biochar could activate the nitrobenzene molecules and accelerate the electron transfer between microbe and nitrobenzene. Additionally, the stimulating level of the biochar on biological nitrobenzene removal remarkably varied under different conditions. Long-term experiments demonstrated that biochar could not only increase nitrobenzene removal rate but also improve the system stability, which may be related to the shift of microbial communities that the relative abundance of nitrobenzene reduction related bacteria as well as electrochemically active bacteria was enriched in biochar addition systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single atom Co-anchored nitrogen‑doped graphene was developed for PMS activation. • 1O 2 generation was boosted in PMS activation and dominant for pollutant degradation. • The acute toxicity of pollutants was effectively reduced in PMS activation. • Developed catalyst exhibited remarkable cycling stability and negligible leaching. Singlet oxygen (1O 2) is an excellent active species generated in advanced oxidation processes (AOPs) that exhibits high selectivity, long life and wide pH tolerance. Therefore, catalysts for highly efficient and selective generation of 1O 2 in AOPs would be highly desirable. This study developed a single atom Co-anchored nitrogen‑doped graphene (Co SAC -NG), which showed excellent catalytic performance for peroxymonosulfate (PMS) activation and bisphenol A degradation, with the pseudofirst-order reaction rate constant improved from 8.13 × 10−4 min−1 without catalyst to 4.42 × 10−2 min−1 with 5 mg L−1 Co SAC -NG. Mechanism studies indicated that Co SAC -NG selectively enhanced 1O 2 generation, which was the dominant active specie for pollutant degradation. Moreover, the Co SAC -NG/PMS system effectively reduced the acute toxicity of pollutant, and Co SAC -NG exhibited remarkable cycling stability and negligible leaching. This study develops a new catalyst with high selectivity for 1O 2 generation and provides a reference for application of single atom catalyst in PMS-based AOPs. [ABSTRACT FROM AUTHOR]

• Pd is doped into the CeMnO bulk lattice by an optimized co-precipitation (CP). • CP outperforms impregnation for CH 4 combustion and CH 4 -related three-way reactions. • Pd in PdCeMnO-CP is partially exsoluted, with lowered valence, after CH 4 combustion. • Surface oxygen vacancy is enriched after CH 4 combustion over PdCeMnO-CP. Besides the Pd/Al 2 O 3 , the Pd-CeO 2 catalysts are the indispensable and promising candidates for methane combustion. The Pd-CeO 2 composites with intimate interaction realized by elaborate methods are regarded as the most active formulations. However, more facile and cost-efficient methods are needed for industrial application. Herein, the Pd was incorporated into the lattice of the Mn-doped CeO 2 by an optimized co-precipitation method to synthesize the PdCeMnO-CP catalyst. The PdCeMnO-CP showed much higher catalytic activity with the T 10 decreased by 70 °C than that of the Pd/CeMnO-Imp prepared with impregnation. The partial exsolution of the initially doped Pd species and the lowered valence of Pd (from Pd4+ to Pdδ+, δ: 2 ∼ 4) during the reaction were confirmed by the low-temperature CO-DRIFTs, CO-pulse chemisorption, XRD and XPS, which were responsible for the activity enhancement. The undercoordinated Ce4+ species were generated during the reaction, thus improving the mobility of the lattice oxygen which is vital for the methane combustion following the MvK mechanism. The PdCeMnO-CP also showed higher activity for the complex methane-containing three-way catalytic reactions than the Pd/CeMnO-Imp, demonstrating its potential for industrial application. [ABSTRACT FROM AUTHOR]

• NH 3 - or urea-treatment turned out to be able to improve Pd-based TWC activity. • Loading pre-precipitated Pd(OH) 2 onto oxides (Urea-PP) offers the best activity. • A facile CO-TPR was developed to replace H 2 -TPR for OSC and reducibility test. • Outer layer coating is necessary to protect the highly sensitive inner layer. Contrary to the stereotype that exposure to NH 3 or urea should be strictly avoided when preparing three-way catalysts using Pd due to Pd2+-NH 3 coordination, remarkable catalytic activity improvement was realized with careful NH 3 or urea treatment towards the oxides support or Pd precursor. And with the help of a newly designed facile CO temperature-programmed reduction (TPR) method, developed to replace traditional H 2 -TPR, it was found that the catalytic activity is closely related with the catalyst reducibility and total oxygen storage capacity (OSC, represented by the integrated area of a CO-TPR curve), thus showing the potential of this CO-TPR method for screening candidate catalysts. When applying the most effective "Urea-PP" technology during monolith converter preparation, this method could no longer show its advantage, unless an outer layer was coated to protect the highly active but also highly sensitive inner layer. [ABSTRACT FROM AUTHOR]

• Pd/Ba-Al 2 O 3 is an excellent catalytic material for wet methane oxidation. • The location, size, valence and property of Pd are controlled by Ba through a two-step impregnation process. • The active metal Pd inside the porous channel makes the catalyst show superior resistance toward H 2 O. • The introduction of Ba enhances the O 2 activation ability of the catalyst. • The low temperature wet methane oxidation depends on the partial pressures of O 2 and H 2 O, but not on those of CH 4 and CO 2. Low temperature wet methane oxidation is critical for the after-treatment of exhaust from the vehicles powered with natural gas-fueled engine, which is always operated at low temperatures and with high water vapor concentrations. Herein, Pd/Ba-Al 2 O 3 catalysts were prepared, with different amount of Ba as the promoter. It was found that the Pd/Ba-Al 2 O 3 catalysts were superior to the reference Ba-free Pd/Al 2 O 3 catalyst in terms of methane conversion, intrinsic activity and hydrothermal stability. Based on the sufficient characterization results, the location, size, valence state and diverse properties of Pd regulated by Ba were revealed. The benefit from Ba addition on the catalytic performance was demonstrated to be derived from the favorable location of Pd inside the porous channel and the enhancement in the capability for O 2 activation. This work can provide insights into the effect of promoters on the catalysts, offer an avenue to designing highly efficient wet methane oxidation catalyst, and lay a foundation for the application of Pd/Ba-Al 2 O 3 in exhaust after-treatment for the natural gas-fueled vehicles. [ABSTRACT FROM AUTHOR]

A novel atomically dispersed Pt into SnO 2 nanocatalyst has been designed by a facile hydrothermal crystallization process to achieve high selective electrochemical reduction of CO 2. Such catalyst can could induce charge redistribution and the formed low-coordinated Pt atoms tune the product selectivity, resulting in the high Faradaic efficiency of HCOOH of 82.1% at −1.2 V vs. RHE. [Display omitted] • Atomically dispersed Pt into SnO 2 nanocatalyst (Pt atom/SnO 2). • Pt atom/SnO 2 promotes the adsorption of intermediates CO 2 *, HCOO* and HCOOH*. • Pt atom/SnO 2 facilitates the conversion of CO 2 to HCOO* rather than HER. • FE HCOO - reaches 82.1% on the obtained sample at −1.2 V vs. RHE. Electrochemical reduction of CO 2 into fuels offers an attractive approach to environmental and energy sustainability. Herein, we designed atomically dispersed Pt into SnO 2 catalyst (Pt atom/SnO 2). Such catalyst dramatically improves the adsorption performance of CO 2 and lowers the activation energy of CO 2. DFT calculations indicate that the doping of Pt in SnO 2 could induce charge redistribution and tune active electronic state, showing higher adsorption energy for intermediates CO 2 *, HCOO* and HCOOH*, which is different from the Pt NPs loaded SnO 2 mainly for H 2 generation. As a result, a higher Faradaic efficiency (82.1 ± 1.4%) and the production rate (5105 μmol h−1 cm−2) of HCOO– are achieved at −1.2 V vs. RHE. Moreover, the current density and Faradaic efficiency of HCOO– nearly remain unchanged in 8 h on the Pt atom/SnO 2 , indicating its high stability. This work opens up a new avenue to tune product selectivity by atomically dispersed catalysts. [ABSTRACT FROM AUTHOR]