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Abstract: Removing harmful species from water is essential for the protection of the environment and human health. Among various treatment techniques, adsorption is particularly attractive because of its advantages of easy operation, high removal efficiency, environmental friendliness, and simple regeneration of the adsorbent. As the key factor of this technique, the choice of adsorbent is vital. Metal-organic frameworks (MOFs) have been widely used as adsorbents to remove dyes, pharmaceuticals and personal care products (PPCPs), and metal ions from aqueous solutions because of their high porosity, structural diversity, and highly tunable pore shape/size and surface functionality. This work systematically reviews the recent progress on applying different types of MOFs, e.g., ZIF, MIL, and UiO series, in the field of adsorption of these harmful species. Modification of novel MOF materials can greatly improve their adsorption performance. This review provides a direction for the rational design of MOF adsorbents to effectively remove various pollutants from water.

This work reports an efficient NiS

A strategy of improving the stability and tuning the activity of transition metal catalysts via nitrogen-doped graphene encapsulation and heteroatomic doping is elaborated here. This work makes for achieving precise regulation of electrocatalysts.

Preparing low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction using a simple strategy still faces challenges. In this work, we proposed a facile phosphating process to successfully transform CoFe-BTC (BTC = 1,3,5-benzenetricarboxylate) precursors into carbon-incorporated bimetallic phosphide (CoFe-P/C) nanospheres. Due to the synergistic effect between bimetals and uniformly covered carbon shells outside, the as-synthesized porous bimetallic phosphide nanospheres exhibit superior HER activity, enhanced kinetics, and excellent cycle durability in both acidic and alkaline solutions. The optimized material could afford a current density of 10 mA cm

N-doped graphene with nano-sized holes possesses abundant electrochemically active sites at the exposed edge and an open porous structure, leading to a better electrochemical performance and faster electron and ion transport than the basal planes in graphene. In this study, three-dimensional graphene with a porous structure and abundant doped N (3d-NHG) were synthesized as bifunctional electrodes for methyl parathion (MP) detection and supercapacitors. The roles of N-doping and the holey construction in the electrochemical performance of the 3d-NHG were systematically investigated through a combined theory-experiment strategy. The 3d-NHG-based electrochemical sensor successfully detected methyl parathion in the range of 38 nm-380 μM with a low detection limit (2.27 nM) and superior sensitivity. Furthermore, the 3d-NHG also demonstrated potential for use in supercapacitors with a specific capacitance of 207 F g

CoP and FeCoP2 exhibit a similar equilibrium crystal shape and facet-dependent activity toward the O2 reduction reaction, but the activity varies.

Hydrazine fuel cells are promising sustainable power sources. However, the high price and limited reserves of noble metal catalysts that promote the sluggish cathodic and anodic electrochemical reactions hinder their practical applications. Reflecting the enhanced diffusion and improved kinetics of nanostructured non-noble metal electrocatalysts, we report an efficient zeolitic-imidazole framework-derived trifunctional electrocatalyst for hydrazine oxidation, oxygen, and hydrogen peroxide reduction. Experimental results and theoretical calculations corroborate that the nanocarbon architecture with abundant Co-N species enhances the electronic interaction and optimizes the energy barriers of anodic hydrazine oxidation and cathodic oxygen reduction. The resulting assembled hydrazine-oxygen fuel cell yields a cell voltage and power density of 0.74 V and 20.5 mW cm-2, respectively. Moreover, benefiting from the liquid-liquid diffusion, the hydrazine-hydrogen peroxide cell shows a boosted cell voltage and power density, corresponding to 1.68 V and 41.0 mW cm-2. This work offers a highly active non-noble metal multifunctional electrocatalyst with a pioneering diffusion philosophy in the liquid electrochemical cells.

The design and synthesis of low-cost and efficient bifunctional electrocatalysts for water splitting are critical and challenging. Hereby, a bimetallic phosphide embedded in a N and P co-doped porous carbon (FeCoP2@NPPC) material was synthesized by using sustainable biomass-derived N- and P-containing carbohydrates and non-noble metal salts as precursors. The obtained material exhibits good catalytic activities in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. The bimetallic alloy phosphide (FeCoP2) is the active site for electrocatalysis. Theoretical calculation indicates that the sub-layer Fe atoms and top-layer Co atoms in FeCoP2 exhibit a synergistic effect for enhanced electrocatalytic performance. The carbon matrix around the FeCoP2 can prevent the corrosion during the catalytic reactions. The hierarchically porous structure of the FeCoP2@NPPC material can promote the transfer of electrons and electrolyte, and increase the contact area of the active sites and electrolytes. N- and P-containing functionalities improve the wetting and conductivity properties of the porous carbon. Due to the synergistic effects, FeCoP2@NPPC requires a low overpotential of 114 and 150 mV at the current density of 10 mA cm-2 for HER in 0.5 M H2SO4 and 1.0 M KOH, and an overpotential of 236 mV for OER in 1.0 M KOH solution, which are much lower than those of FeP@NPPC and CoP@NPPC. Based on the density functional theory calculation, FeCoP2 yields the smallest Gibbs free energy change of rate-determining step among the samples, which leads to better electrochemical performances. In addition, when FeCoP2@NPPC was used as a bifunctional catalyst in water splitting, the electrolyzer needed a low voltage of 1.60 V to deliver the current density of 10 mA cm-2. Furthermore, this work provides a strategy for preparing sustainable, stable, and highly active electrocatalysts for water splitting.

Oxidative coupling of methane (OCM) catalyzed by MnO

Supramolecular hydrogels with stimuli-responsive behaviors under aqueous environments are attractive for their potential applications in controlled drug delivery, clinical diagnostics, and tissue engineering. However, there still remain challenges in developing multicomponent hydrogels as a new generation of "smart" soft materials with multiple intelligent functions toward complex biochemical stimuli. In this work, a three dimensional (3D)-nanostructured supramolecular hydrogel was fabricated using a simple and facile strategy via the self-assembly of graphene oxide (GO) nanosheets, poly(vinyl alcohol) (PVA) chains, and G-quartet/hemin (G4/H) motifs. The as-prepared GO/PVA/G4/H hydrogel exhibited a honeycomb-like 3D GO network architecture as well as excellent mechanical properties. Importantly, the hydrogel demonstrated pH-inducing reversible and cyclic phase transitions between solution and hydrogel states, which could be used as "ink" for injectable 3D printing of different shaped patterns. Also, binary AND and OR logic gates were successfully built by encapsulating enzymes into the hydrogels, which responded to a variety of biochemicals. In addition, the hydrogels showed excellent peroxidase-like activity, achieving the ultrasensitive detection of H2O2 at a concentration as low as 100 nM by their deposition on an electrochemical electrode. The design of multicomponent hydrogels opens up an avenue to fabricate novel "smart" soft matter for biological and medical applications.

Defect engineering is a reasonable solution to improve the surface properties and electronic structure of nanomaterials. However, how to introduce dual defects into nanomaterials by a simple way is still facing challenge. Herein, we propose a facile two-step solvothermal method to introduce Fe dopants and S vacancies into metal-organic framework-derived bimetallic nickel cobalt sulfide composites (NiCo-S). The as-prepared Fe-doped NiCo-S (Fe-NiCo-S) possesses improved charge storage kinetics and activities as electrode material for supercapacitors and the oxygen evolution reaction (OER). The obtained Fe-NiCo-S nanosheet has a high specific capacitance (2779.6 F g-1 at 1 A g-1) and excellent rate performance (1627.2 F g-1 at 10 A g-1). A hybrid supercapacitor device made of Fe-NiCo-S as the positive electrode and reduced graphene oxide (rGO) as the negative electrode presents a high energy density of 56.0 Wh kg-1 at a power density of 847.1 W kg-1 and excellent cycling stability (capacity retention of 96.5% after 10,000 cycles at 10 A g-1). Additionally, the Fe-NiCo-S composite modified by Fe doping and S vacancy has an ultralow oxygen evolution overpotential of 247 mV at 10 mA cm-2. Based on the density functional theory (DFT) calculation, defects cause more electrons to appear near the Fermi level, which is conducive to electron transfer in electrochemical processes. Our work provides a rational strategy for facilely introducing dual defects into metal sulfides and may provide a novel idea to prepare electrode materials for energy storage and energy conversion application.

Oxygen-deficient oxide supports enhance the electron density of InNi3C0.5, enabling efficient CO2 hydrogenation to methanol., Direct CO2 hydrogenation to methanol using renewable energy–generated hydrogen is attracting intensive attention, but qualifying catalysts represents a grand challenge. Pure-/multi-metallic systems used for this task usually have low catalytic activity. Here, we tailored a highly active and selective InNi3C0.5/ZrO2 catalyst by tuning the performance-relevant electronic metal-support interaction (EMSI), which is tightly linked with the ZrO2 type–dependent oxygen deficiency. Highly oxygen-deficient monoclinic-ZrO2 support imparts high electron density to InNi3C0.5 because of the considerably enhanced EMSI, thereby enabling InNi3C0.5/monoclinic-ZrO2 with an intrinsic activity three or two times as high as that of InNi3C0.5/amorphous-ZrO2 or InNi3C0.5/tetragonal-ZrO2. The EMSI-governed catalysis observed in the InNi3C0.5/ZrO2 system is extendable to other oxygen-deficient metal oxides, in particular InNi3C0.5/Fe3O4, achieving 25.7% CO2 conversion with 90.2% methanol selectivity at 325°C, 6.0 MPa, 36,000 ml gcat−1 hour−1, and H2/CO2 = 10:1. This affordable catalyst is stable for at least 500 hours and is also highly resistant to sulfur poisoning.

Single-metal-atom catalysts supported on graphdiyne (GDY) exhibit great potential for catalyzing low temperature CO oxidation in solving the increasingly serious environmental problems caused by CO emissions due to the high catalytic activity, clear structure, uniform metal distribution and low cost. First principle calculations were employed to study CO oxidation activities of four M@GDY single-atom catalysts (M = Pt, Rh, Cu, and Ni). For each catalyst, five possible reaction mechanisms including bi-molecular and tri-molecular reactions were discussed. According to the calculated reaction barriers, the preferred reaction pathway is via the bi-molecular Langmuir–Hinshelwood (BLH) ((CO + O2)* → OCOO* → CO2 + O*) route to yield the first CO2 molecule with 0.55, 0.51, and 0.53 eV as the energy barriers of the rate-limiting steps of Pt@GDY, Rh@GDY, and Cu@GDY, respectively, whereas for Ni@GDY, it switches to the tri-molecular Eley–Rideal (TER1) ((2CO)* + O2 → OCOOCO* → 2CO2) mechanism with the reaction barrier of the rate-limiting step being 1.27 eV. Based on the energy difference in the initial states of the five reaction mechanisms, TER1 is generally viable. No matter it is based on the calculated reaction barrier or the energy of the initial state of each mechanism, the non-noble Cu@GDY is supposed to be an efficient catalyst as the noble ones. The electronic properties are calculated to explain the bonding strength and origin of the catalytic performance. The GDY support plays an important role in the electron transfer process.

The design and synthesis of low-cost and efficient bifunctional electrocatalysts for water splitting are critical and challenging. Hereby, a bimetallic phosphide embedded in a N and P co-doped porous carbon (FeCoP

Summary: CO2 circular economy is urgently calling for the effective large-scale CO2 reutilization technologies. The reverse water-gas shift (RWGS) reaction is the most techno-economically viable candidate for dealing with massive-volume CO2 via downstream mature Fischer-Tropsch and methanol syntheses, but the desired groundbreaking catalyst represents a grand challenge. Here, we report the discovery of a nano-intermetallic InNi3C0.5 catalyst, for example, being particularly active, selective, and stable for the RWGS reaction. The InNi3C0.5(111) surface is dominantly exposed and gifted with dual active sites (3Ni-In and 3Ni-C), which in synergy efficiently dissociate CO2 into CO* (on 3Ni-C) and O* (on 3Ni-In). O* can facilely react with 3Ni-C-offered H* to form H2O. Interestingly, CO* is mainly desorbed at and above 400°C, whereas alternatively hydrogenated to CH3OH highly selectively below 300°C. Moreover, this nano-intermetallic can also fully hydrogenate CO-derived dimethyl oxalate to ethylene glycol (commodity chemical) with high selectivity (above 96%) and favorable stability. : Chemical Reaction; Catalysis; Nanomaterials Subject Areas: Chemical Reaction, Catalysis, Nanomaterials

Supercapacitors (SCs), one of the most popular types of energy-storage devices, present lots of advantages, such as large power density and fast charge/discharge capability. Being the promising SCs electrode materials, metal–organic frameworks (MOFs) and their derivatives have gained ever-increasing attention due to their large specific surface area, controllable porous structure and rich diversity. Herein, the recent development of MOFs-based materials and their application in SCs as the electrode are reviewed and summarized. The preparation method, the morphology of the materials and the electrical performance of various MOFs and their derivatives (such as carbon, metal oxide/hydroxide and metal sulfide) are briefly discussed. Most of recent works concentrate on Ni-, Co- and Mn-MOFs and their composites/derivatives. Conclusions and our outlook for the researches are also given, which would be a valuable guideline for the rational design of MOFs materials for SCs in the near future.

Functionalization of metal–organic framework (MOF) ligands can tune the adsorption properties of MOFs. The adsorptions of NO, NO2, NH3, C5H5N, C4H5N, and C4H4O on pristine and five X-functionalized HKUST-1, i.e. Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate) (X = CH3, CH3O, NH2, NO2, and Br) are evaluated by van der Waals corrected density functional theory calculations. Despite the fact that the open metal center is the energetically preferred adsorption site for most of them, the functional group site can yield a comparable adsorption ability with the open metal center. This is particularly true for pyrrole C4H5N adsorption on CH3O-functionalized HKUST-1 where the functional group site shows stronger adsorption stability than the open metal center site, probably due to the formed hydrogen bond between pyrrole and the CH3O functional group. While the CH3- or CH3O-functionalized organic linker in these MOFs strengthens the adsorption of all the considered species, that of NO2-, Br-, or NH2-functional groups reduces, which is associated with their topologies. Among them, only CH3- or CH3O-functionalized HKUST-1 presents the fmj (orthorhombic crystal system) topology while all the others are isostructural to the pristine HKUST-1 with the tbo (twisted boracite-type, cubic) topological structure. Among six adsorbates, two basic adsorbates, C5H5N and NH3, always yield the strongest bonding strength upon adsorption on the pristine and five functionalized HKUST-1. Electronic properties including the Bader charges, electron density differences, and electron localization function were investigated to comprehend their adsorption behaviors. This work provides guidance for the proper functionalization of HKUST-1 with improved adsorption properties for specific adsorbates.

High mass loading metal–organic frameworks (MOFs) exhibit great potentials as electrode materials in energy storage, benefiting from their massive exposed reactive sites. Keeping high mass loadings while maintaining ultra-fine morphology of MOFs is very technically demanding. Herein, high mass loading binder-free NiCo-MOFs with mixed organic linkers (1,3,5-benzenetricarboxylate, BTC and p-benzenedicarboxylate, PTA) have been in-situ grown on Ni foam (NF) using Co(OH)2 as the template. The designed NiCo-(PTA)0.8(BTC)0.2 nanosheets achieved an areal capacitance of 5.84 F cm−2 (2.92 C cm−2) at a current density of 1 mA cm−2. The origin of the excellent electrochemical performances is carefully explained. The fabricated asymmetric supercapacitor (ASC) using NiCo-(PTA)0.8(BTC)0.2 nanosheets and reduced graphene oxide (rGO) as the positive and negative electrodes presented an excellent specific capacitance of 113 F g−1 at 1 A g−1. Besides, an outstanding energy density of 40 Wh kg−1 was achieved at the power density of 800 W kg−1. The assembled ASC device can retain as high as 97.7% of the original capacitance after 10,000 cycles, manifesting an excellent cycle stability. This work may provide a strategy for the preparation of high mass loading dual metal MOFs electrodes with ultra-fine morphology for high-performance supercapacitors.

A high-performance Ni-foam-structured nano-intermetallic InNi3C0.5 catalyst is developed for the gas-phase hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). The InNi3C0.5/Ni-foam catalyst is obtainable by hydrothermal growth of NiC2O4 onto the Ni-foam, impregnation with In2O3 precursor, subsequent calcination and carburization in a syngas. Despite DMO cascade hydrogenation to MG, then to EG, and finally to EtOH, such catalyst hydrogenates DMO dexterously until to EG with a high turnover frequency of 636 h−1, because the 3Ni-In and 3Ni-C sites on InNi3C0.5(1 1 1) effectively activate DMO but hinder EG over-hydrogenation to EtOH. Favorable reaction pathway on the InNi3C0.5(1 1 1) surface predicted theoretically is DMO* → CH3OCOCO* → CH3OCOCHO* → CH3OCOCHOH* → MG* → CH3OCHOCH2OH* → CHOCH2OH* → HOCHCH2OH* → EG*. Moreover, the neutral Ni-foam diminishes the formation of ethers and diols. This catalyst achieves full DMO conversion with 96–98% EG selectivity and is stable for at least 2500 h under industrial-relevant conditions, and can also hydrogenate a broad scope of carbonyl compounds to corresponding alcohols with high yields.

The interfacial stability of copper/diamond directly affects its mechanical properties and thermal conductivity. The atomic structures and electronic properties of Cu/diamond and Cu/X/diamond interfaces have been identified to investigate the effect of interfacial additive X (X = Ni or N) on the low-index interfacial adhesion of copper/diamond composites. For unmodified composites, the interfacial stability decreases in the order of Cu(0 0 1)/diamond(0 0 1) Cu(1 1 1)/diamond(1 1 1) Cu(0 1 1)/diamond(0 1 1). The metallic interfacial additive Ni is found to enhance the Cu(0 1 1)/diamond(0 1 1) interfacial stability and exchange the interfacial stability sequence of (0 1 1) and (1 1 1) composites. The nonmetallic element N will promote the stability of Cu(1 1 1)/diamond(1 1 1) but not alter the stability order of the composites at different interfaces. To explain the origin of interfacial stability, a series of analyses on atomic structures and electronic properties have been carried out, including the identification of the type of formed interfacial boundaries, the measurement of interfacial bond lengths, and the calculations of density of states, bond populations, and atomic charge. The stability of the interface is found to be related to the type of formed interfacial boundary and bond, the interfacial bond populations, and the interfacial bond numbers. The layer-projected density of states reveals that all of the considered interfaces exhibit metal characteristics. The interfacial Ni additive is found to be an electron donor contributing the electrons to its bonded Cu and C atoms while the interfacial N atom is an electron acceptor where it mainly accepts the electrons from its bonded Cu and C.

Hierarchical FeP nanoarray films composed of FeP nanopetals were successfully synthesized via a bio-inspired hydrothermal route followed by phosphorization. Glycerol, as a crystal growth modifier, plays a significant role in controlling the morphology and structure of the FeO(OH) precursor during the biomineralization process, while the following transfer and pseudomorphic transformation of the FeO(OH) film successfully give rise to the FeP array film. The as-prepared FeP film electrodes exhibit excellent hydrogen evolution reaction (HER) performance over a wide pH range. Theoretical calculations reveal that the mixed P/Fe termination in the FeP film is responsible for the high catalytic activity of the nanostructured electrodes. This new insight will promote further explorations of efficient metal phosphoride-based catalysts for the HER. More importantly, this study bridges the gap between biological and inorganic self-assembling nanosystems and may open up a new avenue for the preparation of functional nanostructures with application in energy devices.

During the past decades, nano-structured metal oxide electrode materials have received growing attention due to their low development cost and high theoretical specific capacity, accordingly, quite a lot of metal oxide electrode materials are being used in electrochemical energy storage devices. However, the further development was limited by the relatively low electrical conductivity and the volume expansion during electrochemical reactions. Thus, many approaches have been proposed to obtain high-efficiency metal oxide electrode materials, such as designing nanomaterials with ideal morphology and high specific surface area, optimizing with carbon-based materials (such as graphene and glucose) to prepare nanocomposites, combining with conductive substrates to enhance the conductivity of electrodes, etc. Owning to the advantages of low cost and high chemical stability of carbon materials, core-shell structure formed by carbon-coated metal oxides is considered to be a promising solution to solve these problems. Therefore, this review mainly focuses on recent research advances in the field of carbon-coated metal oxides for energy storage, summarizing the advantages and disadvantages of common metal oxides and different types of carbon sources, and proposing methods to optimize the material properties in terms of structure and morphology, carbon layer thickness, coating method, specific surface area and pore size distribution, as well as improving electrical conductivity. In addition, the double or multi-layer coating strategy is also a reflection of the continuous development of carbon coating method. Hopefully, this rereview may provide a new direction for the renewal and development of future energy storage electrode materials.

Ethylidyne, ethane, and carbon monomer formations from ethylene over Ir(111) at different coverages are investigated using density functional theory methods. Two possible reaction mechanisms for ethylidyne formation are investigated. The calculations show that vinyl prefers the dehydrogenation to yield vinylidene (M2) over the hydrogenation to produce ethylidene (M1) kinetically and thermodynamically at 1/9 (1/3) ML. Ethylidyne formation could be a competitive side reaction of ethylene hydrogenation, however, the ethylidyne species does not directly participate in the ethylene hydrogenation mechanism. The mechanism for C monomer formation is also studied. Microkinetic modeling shows that the ethylene hydrogenation reactivity decreases in the sequence Ir(111)>Rh(111)>Pd(111)>Pt(111) under typical hydrogenation conditions. The catalytic activity of ethylene hydrogenation decreases with increased stability of ethylene adsorption and reaction barrier of the rate-limiting step.

Summary CO2 circular economy is urgently calling for the effective large-scale CO2 reutilization technologies. The reverse water-gas shift (RWGS) reaction is the most techno-economically viable candidate for dealing with massive-volume CO2 via downstream mature Fischer-Tropsch and methanol syntheses, but the desired groundbreaking catalyst represents a grand challenge. Here, we report the discovery of a nano-intermetallic InNi3C0.5 catalyst, for example, being particularly active, selective, and stable for the RWGS reaction. The InNi3C0.5(111) surface is dominantly exposed and gifted with dual active sites (3Ni-In and 3Ni-C), which in synergy efficiently dissociate CO2 into CO* (on 3Ni-C) and O* (on 3Ni-In). O* can facilely react with 3Ni-C-offered H* to form H2O. Interestingly, CO* is mainly desorbed at and above 400°C, whereas alternatively hydrogenated to CH3OH highly selectively below 300°C. Moreover, this nano-intermetallic can also fully hydrogenate CO-derived dimethyl oxalate to ethylene glycol (commodity chemical) with high selectivity (above 96%) and favorable stability., Graphical Abstract, Highlights • InNi3C0.5 catalyst is highly active, selective, and stable for the RWGS reaction • InNi3C0.5(111) surface is gifted with dual active sites (3Ni-In and 3Ni-C) • CO2 is dissociated into CO* (preferentially desorbed) on 3Ni-C and O* on 3Ni-In • InNi3C0.5 is also promising for application in carbonyl-to-hydroxyl processes, Chemical Reaction; Catalysis; Nanomaterials

CO oxidation on single-atom alloys (SAAs) surfaces is of potential importance in automobile industry. The relatively simple mechanism of CO oxidation reaction and the well-organized possible active sites in SAAs enable accurate modeling with theory, making the rational design of SAAs catalysts feasible. Van der Waals density functional theory (DFT), combined with micro-kinetic modelling, is used to study CO oxidation on 12 M-Ni(111) SAAs and pure Ni(111) surfaces. On Fe-, Co-, Ru-, Rh-, and Ir-Ni(111) SAAs surfaces, CO oxidation takes place over the region containing the alloying atom, while for the other SAAs, it occurs at the pure-Ni area. Micro-kinetic modelling reveals that Rh-Ni(111) SAA surface presents the largest reaction rate, followed by Au-Ni(111) and Ir-Ni(111) under our considered reaction conditions, consistent with the experimental observations on the corresponding nanoparticles. Among 12 SAAs, only Zn-Ni(111), Cu-Ni(111), and Cd-Ni(111) yields the poorer catalytic activity than pure Ni(111) for CO oxidation. The origin of catalytic reactivity sequence of SAAs for CO oxidation is discussed from the analyses of rate-limiting steps, electronic property and alloying effects.

Oxygen chemisorption on β–Mo 2 C surfaces, the subsequent CO/CO 2 desorption and oxygen diffusion to the carbon vacancy have been investigated by density-functional theory. The most stable structures together with the energetics of oxygen stepwise adsorption, CO/CO 2 desorption and oxygen diffusion to the carbon vacancy were identified. We examined the effect of oxygen coverage on the morphology of β–Mo 2 C by plotting the equilibrium crystal shape. Thermodynamic effect of temperature and reactant or product pressure on the CO/CO 2 desorption were investigated. The CO/CO 2 desorption is more favorable at the saturated oxygen coverage than the low oxygen coverage thermodynamically. The subsequent oxygen diffusion to the carbon vacancy after CO/CO 2 desorption may happen depending on the surfaces and oxygen coverage.

Layered-structure MOF is a promising material for electrochemical energy storage applications. However, low conductivity hinders their electrochemical performance. Herein, a hierarchical layered-structure CoNi-MOF with ultrathin nanosheets and nanotube arrays are directly grown on carbon cloth (CC) with Co(OH)2 as both template and Co source. The synthesized CC/CoNi-MOF shows high areal capacity of 1.01 C cm−2 at 2 mA cm−2, while keeps 61.4% capacity retention at 15 mA cm−2. A hybrid supercapacitor is successfully fabricated with CC/CoNi-MOF as positive electrode and reduced graphene oxide-carbon nanotube as negative electrode, possessing a maximum areal capacitance of 846 mF cm−2 at 1 mA cm−2, a high energy density of 55.5 Wh kg−1 at 175.5 W kg−1, and excellent cycling stability (96.5% after 10000 cycles). This work may pave a new way for designing MOF based materials with similar structure for high performance supercapacitors.

BC5 with both superhard and superconducting properties is expected to have important applications in many fields. In this work, the low-index surface structures and properties of BC5 have been identified by first-principles calculations. The surface stability decreased in the order of (011) > (010) > (101) > (100) > (110) > (111) > (001). The (011), (101), and (110) surfaces exhibit the strongest surface relaxation, followed by (111), and the (001) surface is the least. A DFT (density functional theory)-based Wulff construction of the equilibrium shape of BC5 shows that the surface with the largest exposure area is (011), followed by the (101) and (001) surfaces. Electronic analyses show that Pmma phase BC5 and all considered low-index surfaces exhibit metallic character where the surfaces are even stronger. Larger charge redistribution in the low-index surfaces is found compared with the bulk case.

The “surface explosion” associated with decomposition of acetic acid on Rh surfaces is studied by density functional theory. The surface configuration of adsorbed acetate and the reaction paths available to the adsorbed species are determined. The reactivity of adsorbed acetate is found to be dependent on the local surface coverage, which allows a model explaining the experimentally observed surface explosion to be developed. Comparison of the reactivity of different surfaces shows that Rh(111) is more active than the Rh(110) surface for both clean and oxygen precovered surfaces, and the oxygen precovered surfaces are less active than the clean surfaces.

An inverse Pd–Zr model catalyst was prepared by chemical vapor deposition (CVD) using zirconium-t-butoxide (ZTB) as an organometallic precursor. Pd–Zr interaction was then investigated with focus on the correlation of reforming performance with the oxidation state of Zr. As test reactions, dry reforming of methane (DRM) and methanol steam reforming (MSR) were chosen. Depending on treatments, either ZrOxHy or ZrO2 overlayers or Zr as sub-nanometer clusters could be obtained. Following the adsorption of ZTB on Pd(111), a partially hydroxylated Zr4+-containing layer was formed, which can be reduced to metallic Zr by thermal annealing in ultrahigh vacuum, leading to redox-active Zr0 sub-nanometer clusters. Complementary density functional theoretical (DFT) calculations showed that a single layer of ZrO2 on Pd(111) can be more easily reduced toward the metallic state than a double- and triple layer. Also, the initial and resulting layer compositions greatly depend on gas environment. The lower the water background partial pressure, the faster and more complete the reduction of Zr4+ species to Zr0 on Pd takes place. Under methanol steam reforming conditions, water activation by hydroxylation of Zr occurs. In excess of methanol, strong coking is induced by the Pd/ZrOxHy interface. In contrast, dry reforming of methane is effectively promoted if these initially metallic Zr species are present in the pre-catalyst, leading to a Pd/ZrOxHy phase boundary by oxidative activation under reaction conditions. These reaction-induced active sites for DRM are stable with respect to carbon blocking or coking. In essence, Zr doping of Pd opens specific CO2 activation channels, which are absent on pure metallic Pd.

Comprehending the bond nature of ethylene-metal clusters at the atomic level is important for the design of nanocatalysts and their applications in the fields of fine chemistry and petroleum refining. The growth of Irn (n = 1&ndash, 10) on &gamma, &ndash, Al2O3(110) and ethylene adsorption on bare and &gamma, Al2O3(110)-supported Irn (n = 1&ndash, 10) clusters were investigated using the density functional theory (DFT) approach. The mode stability of ethylene adsorption on the bare Irn clusters followed the order &pi, &gt, di-&sigma, B-T, with the exception of Ir8 where the &pi, structure was less stable than the di-&sigma, configuration. On supported Irn (n = 4&ndash, 7 and 10) the stability sequence was &pi, &prime, (at interface), while on supported Irn (n = 2, 3, 8, and 9) the sequence changed to di-&sigma, &pi, (at interface). Two-thirds of ethylene adsorption on the supported Irn clusters were weaker than its adsorption on the bare Irn clusters. The pre-adsorbed ethylene at the interface was found to facilitate the nucleation from the even-sized supported Irn to odd-sized Irn clusters, but hindered the nucleation from the odd-sized Irn to even-sized Irn clusters.

The formation of surface species from two- and three-carbon polyols on γ-Al2O3 in the presence and absence of coadsorbed water is investigated. Aqueous-phase adsorption isotherms indicate that competitive adsorption between water and polyol inhibits the uptake of the polyol molecules on γ-Al2O3 and that the polyol with the most hydroxyl groups, glycerol, experienced the greatest uptake. Deuterium solid echo pulse NMR measurements support the fact that glycerol strongly interacts with γ-Al2O3 in the presence of physisorbed water and that ethylene glycol interacts with γ-Al2O3 only after the physisorbed water has been removed. In situ high-vacuum FT-IR analysis combined with DFT simulations demonstrate that glycerol readily forms a multidentate alkoxy species through its primary hydroxyl groups with coordinatively unsaturated Al atoms of γ-Al2O3 in the presence of physisorbed water. This surface species exhibits a bridging alkoxy bond from one of its primary hydroxyl groups and a strong interaction with the...