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• Four activated carbon/metal oxides composites (AC/MgO, AC/ZnO, AC/CuO and AC/ZrO 2) were synthesized. • The adsorption performance of AC/MO x composites for three kinds of VOCs (acetone, toluene and methanol) were tested. • ZnO nanoparticles are the most effective for enhancing the VOCs capture performance of activated carbon. • The AC/MO x composites showed strong adsorption to acetone and methanol, but not to toluene. • Adsorption mechanism between VOCs and AC/MO x composites is elucidated by experimental and DFT methods. To enhance the interfacial interaction of activated carbon (AC) with volatile organic compounds (VOCs), the AC surface was modified by depositing metal oxide nanoparticles via an evaporation-induced self-assembly (EISA) method. Taking acetone, toluene and methanol as adsorbates, both dynamic and static VOCs adsorption methods were used to evaluate the adsorption performance of AC and AC/MO x (M = Mg, Zn, Cu and Zr). Compared to pure AC, metal oxide nanoparticles deposition effectively increased the adsorption capacity for acetone and methanol, and AC/ZnO composites showed the best adsorption performance for acetone (415 mg g−1) and methanol (481 mg g−1). In concert with the experiment, a set of systematic theoretical calculations, regarding adsorption energy, adsorption equilibrium distance and charge transfer, were performed to explore the VOCs adsorption mechanism on the metal oxide surface. The adsorption performance can be determined by the Lewis acid-base properties of VOCs-metal oxide systems, the characteristic functional groups and the molecular polarity of VOCs molecules, which paves a new way to develop a novel metal oxide based adsorbent for the VOCs adsorption applications. [ABSTRACT FROM AUTHOR]

• The kilogram-level equipment was used to pilot scale tests of pressure swing adsorption. • The effect of the interaction between adsorption and desorption for pressure swing adsorption properties was analyzed. • The mechanism of pressure swing adsorption for different volatile organic compounds was revealed by serious experiments. • The factors influencing nonequilibrium time, effective length and enrichment ratio were analyzed. • The effect of boiling point on desorption performance under different vacuum degrees was demonstrated by experiments. Volatile organic compounds (VOCs) emissions cause serious health problems and environmental pollution, and pressure swing adsorption (PSA) is one of the most promising technologies for VOCs removal and recovery. Commercial activated carbon and three typical VOCs (methanol, acetone and toluene) were selected as adsorbent and adsorbates, and the kilogram-level equipment was used to perform the pilot scale tests in order to study the application of PSA for removing and recycling VOCs in industry. The mechanism and industrial parameters including nonequilibrium time, effective length and enrichment ratio of PSA for removing and recycling VOCs has been studied by PSA experiments, static adsorption experiments, dynamic adsorption experiments, temperature programmed desorption (TPD) experiments and fitting. The results of PSA show that nonequilibrium time and effective length are related to the kinetic diameter, polarity of adsorbates and pore size, surface functional groups of adsorbents, and enrichment ratio is affected by the above factors and the boiling point of adsorbate. The horizontal comparison of three VOCs showed that methanol and acetone molecules with smaller kinetic diameter and greater polarity only need shorter effective length to removed completely by PSA. At low vacuum, the desorption performance is related to desorption activation energy (methanol 18.62 kJ/mol < acetone 22.20 kJ/mol < toluene 41.15 kJ/mol). At high vacuum, the desorption performance will be improved while the boiling point of adsorbate is lower than the temperature of fixed-bed. Based on this mechanism, the enrichment ratio of acetone can reach 2.1 under the same conditions, so that the recovery ratio of acetone became the highest among these three VOCs. This result provides new opportunities for the removal and recovery of VOCs gases. [ABSTRACT FROM AUTHOR]

• Surface energy of the implants is key to protein adsorption. • Various surface energies were achieved by different structure of oxides. • BAS absorption was affected more by polar component of surface energy. • Electrostatic and hydrophobic interactions control protein adsorption. CoCrMo alloys have been used as biomedical materials for decades. During long-term service in the body environment, however, proteins adsorbing onto the surface of implant can cause their spontaneous corrosion and even the release of toxic ions, which may cause long-term damage to patients. It is essential to understand the key factors affecting protein adsorption and how it can alter corrosion reactions. In this study, the surface energy of a CoCrMo alloy was changed through various oxidation processes. Surface analysis techniques, such as XPS, AES, and GIXRD were used to characterise the chemical properties of the surfaces of modified CoCrMo alloys. Surface topography and potential images of samples after bovine serum albumin (BSA) adsorption were acquired by AFM/SKPFM. The results show that with the increase of the oxidation temperature, the hydrophilicity of the samples was enhanced. With the increase in oxidation time at the same temperature, the surface energy of the samples increased, the dispersion component increased, and the polar component decreased. As a result, the amount of BSA adsorbed on the surfaces decreased, and this was affected more by the polar component than by other components, which was due to the electrostatic and hydrophobic interactions. [ABSTRACT FROM AUTHOR]

• Oxygen and nitrogen co-doped porous carbon/MgO (ONPC@MgO) composites were synthesized. • Acetone is captured by O/N functional groups and MgO by monolayer adsorption at low pressure. • Acetone is adsorbed on the surface of carbon and MgO by multilayer adsorption at high pressure. • Adsorption mechanism between acetone and ONPC@MgO composites is elucidated by experimental and DFT methods. The amount of anthropogenic volatile organic compounds (VOCs) emission keeps increasing worldwide, and it urges the development of VOC emission reduction technology. Efficient and environmentally friendly adsorption technology is receiving more interest, and carbon-based materials have attracted enormous attention for VOC capture. However, the poor adsorption capacity and cycling stability still hinder their application. Moreover, the mechanism of adsorption behavior between functionalized carbon surfaces and VOCs has not been investigated in detail. Herein, we report a sustainable and cost-effective method for the anchoring of the MgO nanoparticle onto O/N co-doped porous carbon derived from waste biomass (denoted as MgO@ONPC). The optimized 7%MgO@ONPC composite exhibited an exceedingly high acetone adsorption capacity (859 mg g−1 at 25 °C, 18 kPa) and excellent cycling stability (95.2% capacity retention over 10 cycles). Acetone dynamic breakthrough tests showed that the adsorption capacity of 7%MgO@ONPC composite at 10% breakthrough level (10% BT) and 100% BT was 384 and 508 mg g−1, respectively (in terms of PC: 3.9 × 10−3 and 5.2 × 10−2 mol kg−1 Pa−1, respectively). Isotherm model fitting and quantum chemistry calculation studies indicated O/N functional groups and MgO nanoparticles can significantly improve the acetone monolayer adsorption at low relative pressures due to hydrogen bonds and electrostatic interaction. Highly active MgO nanoparticles and pore structure characteristics are found to be determinative factors for acetone adsorption at high relative pressure. [ABSTRACT FROM AUTHOR]

Highlights • Adsorption of acetone to (MO) 12 (M = Be, Mg, Zn) and their graphene composites. • (ZnO) 12 and its graphene composite are not sensitive to acetone, and the others are. • (MgO) 12 could be an excellent acetone sensor for the sensitivity and recovery time. Abstract Acetone, one of the most common VOCs, could cause serious air pollution and threat the human health when someone is exposed to certain concentration of acetone. Thereof, acetone detection and elimination in the air was significant to prohibit the hazard of acetone. Acetone adsorbed to (BeO) 12 , (MgO) 12 and (ZnO) 12 nanoparticles and their graphene composites was detailed studied by density functional theory. The adsorption energy of acetone to (MO) 12 (M = Be, Mg, Zn) nanoparticles and their graphene composites were high, which means that all the adsorbents are eligible for acetone adsorption. The variation of band gap was utilized to describe the sensibility to acetone. It was found that the (ZnO) 12 nanoparticle and its graphene composite were not sensitive to the acetone, while the (BeO) 12 and (MgO) 12 , as well as their graphene composites, were sensitive to acetone. Among the (BeO) 12 -graphene and (MgO) 12 -graphene, the latter exhibits more sensitive than the former. The conventional transition state theory was been took to estimate the recovery time. According to our calculation, (BeO) 12 and (ZnO) 12 nanoparticles and all (MO) 12 graphene composites have too long recovery time for the high adsorption energy hampering the recovery of the adsorbents. Contrastingly, (MgO) 12 nanoparticle is sensitive to acetone and has receivable recovery time. Therefore, (BeO) 12 , (MgO) 12 and (ZnO) 12 nanoparticles and their graphene composites may be potential adsorbents for acetone adsorption for their relatively high adsorption energy. The (MgO) 12 nanoparticle could be an excellent gas sensor for detecting acetone due to the sensitivity acetone and receivable recovery time. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The relative influence of porous structure and functional groups of porous carbon materials for acetone adsorption is presented in this article. Here, we have successfully prepared oxygen and nitrogen doping porous carbons (ONPCs) by a hydrothermal method using waste tobacco stem as the carbon precursor and ethylenediamine as a nitrogen source. The resulting ONPCs have high specific surface (906–2940 m2 g−1) and chemical compositions (1.80–5.22% N and 5.81–11.77% O). This carbon shows high acetone adsorption capacity (i.e. , 16.91 mmol g−1 at 25 °C and 18 kPa). The pore volume and specific surface area of ONPCs were found to be determinative factors for acetone adsorption at high pressure, and the introduction of oxygen and nitrogen into carbon surface can improve acetone adsorption at low pressure. Molecular simulations results suggest that adsorption capacity of acetone is improved at low pressure after doping of oxygen and nitrogen functional groups, but equilibrium adsorption capacity is unchanged. This is in good agreement with the experimental results that these functional groups are primarily responsible for the materials’ low-pressure acetone adsorption capacity. This work provides insights into material design and further development for acetone adsorption. [ABSTRACT FROM AUTHOR]

• Mechanism of ORR proceeding on different crystal planes of Pt 3 Co is calculated by DFT. • Calculated the Pt 3 Co (1 0 0) has the highest O adsorption energy at site t3. • Seven elementary reactions of ORR on Pt 3 Co (1 1 1) are researched. • Hydrogenation step is rate-determining step activation barrier is 0.61 eV. • Calculated the Pt 3 Co (1 1 1) has the highest Pt vacancy formation energy. Pt 3 Co nanocatalyst shows better oxygen reduction reaction (ORR) activity and durability toward Pt. In this paper, the oxygen adsorption, durability and the ORR mechanism of Pt 3 Co are investigated based on density functional theory (DFT) calculations by CASTEP code. The adsorption energy of O atom at each site on (1 0 0), (1 1 0), and (1 1 1) surfaces indicated that the adsorption strength of O atom on Pt 3 Co surface follows the order (1 0 0) > (1 1 0) > (1 1 1). In addition, the ORR mechanism is explored through the electron density difference, d-band center, and the ORR elementary reactions. The results are consistent with the tendency for adsorption energy and prove that the O hydrogenation step is the rate-determining step on Pt 3 Co (1 1 1). Furthermore, the calculation of surface Pt vacancy formation energy reveals that the Pt 3 Co (1 1 1) catalyst has the best durability. The results could guide the design of surface crystal orientation of Pt 3 Co nanocatalyst for ORR. [ABSTRACT FROM AUTHOR]

• An approach for preparing carbon with both high SSA and high nitrogen content is proposed. • The zinc salt enhances both the stability of melamine melem, and the pore-forming process. • These porous carbons show a remarkable acetone static uptake and capacitor property. Carbon based materials are vital for many scientific applications because of their well-developed pore structure and functionalized surface. However, to achieve high surface area, harsh synthesis conditions, such as the use of high temperatures and corrosive activators, are usually needed, which allows the functional groups to gradually decompose or react in return, resulting in very poor surface chemistry. Herein, a novel and effective approach including the optimized carbonization and activation processes is proposed. The molten zinc salt can not only significantly enhance the stability of the nitrogen source through the strong Lewis acid-base interactions, but also strengthen the pore-forming process. By varying the activating temperature, the as-prepared waste biomass derived porous carbons exhibit an extremely high surface area (up to 4098 m2 g−1) and rich nitrogen contents (from 0.67 to 6.18 wt%). Interestingly, beyond the disordered cross-linked network microtopography, there are numerous unique microsphere and cubic structures decorated on the carbon surface. In terms their potential applications, these porous carbons simultaneously show a record-high acetone static uptake (1678 mg g−1 at 25 °C and 18 kPa) and ultrahigh capacitor property (specific capacitance of 346 F/g−1 and specific energy density of 39.4 Wh/kg−1). [ABSTRACT FROM AUTHOR]