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The nitrate (NO3−) electroreduction into ammonia (NH3) represents a promising approach for sustainable NH3 synthesis. However, the variation of adsorption configurations renders great difficulties in the simultaneous optimization of binding energy for the intermediates. Though the extensively reported Cu-based electrocatalysts benefit NO3− adsorption, one of the key issues lies in the accumulation of nitrite (NO2−) due to its weak adsorption, resulting in the rapid deactivation of catalysts and sluggish kinetics of subsequent hydrogenation steps. Here we report a tandem electrocatalyst by combining Cu single atoms catalysts with adjacent Co3O4 nanosheets to boost the electroreduction of NO3− to NH3. The obtained tandem catalyst exhibits a yield rate for NH3 of 114.0 mg NH 3 h−1 cm−2, which exceeds the previous values for the reported Cu-based catalysts. Mechanism investigations unveil that the combination of Co3O4 regulates the adsorption configuration of NO2− and strengthens the binding with NO2−, thus accelerating the electroreduction of NO3− to NH3. An optimal catalyst for nitrate electroreduction should satisfy the simultaneously optimized adsorption of intermediates. Here, the authors report a tandem electrocatalyst by combining Cu single atoms with Co3O4 nanosheets, enhancing the binding with NO2−, thus promoting nitrate electroreduction to NH3. [ABSTRACT FROM AUTHOR]

Seawater electrolysis offers a renewable, scalable, and economic means for green hydrogen production. However, anode corrosion by Cl- pose great challenges for its commercialization. Herein, different from conventional catalysts designed to repel Cl- adsorption, we develop an atomic Ir catalyst on cobalt iron layered double hydroxide (Ir/CoFe-LDH) to tailor Cl- adsorption and modulate the electronic structure of the Ir active center, thereby establishing a unique Ir-OH/Cl coordination for alkaline seawater electrolysis. Operando characterizations and theoretical calculations unveil the pivotal role of this coordination state to lower OER activation energy by a factor of 1.93. The Ir/CoFe-LDH exhibits a remarkable oxygen evolution reaction activity (202 mV overpotential and TOF = 7.46 O2 s−1) in 6 M NaOH+2.8 M NaCl, superior over Cl--free 6 M NaOH electrolyte (236 mV overpotential and TOF = 1.05 O2 s−1), with 100% catalytic selectivity and stability at high current densities (400-800 mA cm−2) for more than 1,000 h. The seawater oxidation reaction faces challenges from competitive chloride oxidation reaction. Herein, the authors have utilized chlorine adsorption to modulate the single-atom Ir coordination state and promote seawater oxidation and catalyst stability. [ABSTRACT FROM AUTHOR]

The rational design of efficient bifunctional single-atom electrocatalysts for industrial water splitting and the comprehensive understanding of its complex catalytic mechanisms remain challenging. Here, we report a Ni single atoms supported on oxygen-incorporated Mo2C via Ni-O-Mo bridge bonds, that gives high oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) bifunctional activity. By ex situ synchrotron X-ray absorption spectroscopy and electron microscopy, we found that after HER, the coordination number and bond lengths of Ni-O and Ni-Mo (Ni-O-Mo) were all altered, yet the Ni species still remain atomically dispersed. In contrast, after OER, the atomically dispersed Ni were agglomerated into very small clusters with new Ni-Ni (Ni-O-Ni) bonds appeared. Combining experimental results and DFT calculations, we infer the oxidation degree of Mo2C and the configuration of single-atom Ni are both vital for HER or OER. This study provides both a feasible strategy and model to rational design highly efficient electrocatalysts for water electrolysis. The comprehensive understanding of complex catalytic mechanisms under harsh reaction conditions for efficient bifunctional single-atom electrocatalysts remain challenging. Here the authors found microenvironment reconsitution of highly active Ni single atoms on oxygen-incorporated Mo2C for water splitting. [ABSTRACT FROM AUTHOR]

Electrocatalytic acetylene semi-hydrogenation to ethylene powered by renewable electricity represents a sustainable pathway, but the inadequate current density and single-pass yield greatly impedes the production efficiency and industrial application. Herein, we develop a F-modified Cu catalyst that shows an industrial partial current density up to 0.76 A cm−2 with an ethylene Faradic efficiency surpass 90%, and the maximum single-pass yield reaches a notable 78.5%. Furthermore, the Cu-F showcase the capability to directly convert acetylene into polymer-grade ethylene in a tandem flow cell, almost no acetylene residual in the production. Combined characterizations and calculations reveal that the Cuδ+ (near fluorine) enhances the water dissociation, and the generated active hydrogen are immediately transferred to Cu0 (away from fluorine) and react with the locally adsorbed acetylene. Therefore, the hydrogen evolution reaction is surpassed and the overall acetylene semi-hydrogenation performance is boosted. Our findings provide new opportunity towards rational design of catalysts for large-scale electrosynthesis of ethylene and other important industrial raw. Efficient electroreduction of acetylene to ethylene is crucial for industrial applications. Here, the authors reported fluorine modified copper for direct conversion of acetylene to polymer-grade ethylene in one single-pass with industrial-current-density. [ABSTRACT FROM AUTHOR]

Highlights: Oxygen-coordinated single-atom Mn catalyst was fabricated via introducing oxygen functional groups rich bacterial cellulose as the adsorption regulator through a combined impregnation–pyrolysis–etching synthetic route. Mn–O–C as the electrocatalyst exhibits superior electrocatalytic activity toward ammonia synthesis with a maximum NH3 yield rate of 1476.9 ± 62.6 μg h−1 cm−2 at − 0.7 V (vs. RHE) and a faradaic efficiency of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Electrocatalytic mechanism of Mn–(O–C2)4 site for nitrate reduction reaction is unveiled by a combination of in situ spectroscopy characterization and computational study. Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection. Here, we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen (O) coordination on bacterial cellulose-converted graphitic carbon (Mn–O–C). Evidence of the atomically dispersed Mn–(O–C2)4 moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy. As a result, the as-synthesized Mn–O–C catalyst exhibits superior NitRR activity with an NH3 yield rate (RNH3) of 1476.9 ± 62.6 μg h−1 cm−2 at − 0.7 V (vs. reversible hydrogen electrode, RHE) and a faradaic efficiency (FE) of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Further, when evaluated with a practical flow cell, Mn–O–C shows a high RNH3 of 3706.7 ± 552.0 μg h−1 cm−2 at a current density of 100 mA cm−2, 2.5 times of that in the H cell. The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn–(O–C2)4 sites not only effectively inhibit the competitive hydrogen evolution reaction, but also greatly promote the adsorption and activation of nitrate (NO3−), thus boosting both the FE and selectivity of NH3 over Mn–(O–C2)4 sites. [ABSTRACT FROM AUTHOR]

Recently, nanozyme-based sensing platforms have attracted widespread attention due to their excellent performance in practical applications. In this paper, phosphorus-doped porous materials were synthesized by a one-step method and metal-doped with different metal salts. The results show that the iron-containing porous nitrogen-phosphorus material (FeNPC) has the best peroxidase activity. FeNPC catalyzes hydrogen peroxide to generate hydroxyl radical (•OH) which oxidizes colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB. When the above system encounters ferulic acid, the blue product will be inhibited, and the color of the reaction solution will change, so ferulic acid can be detected by the colorimetric method. Ferulic acid is an antioxidant used in humans as an antibacterial and antiviral drug. The detection limit of this colorimetric sensor is as low as 1.3 nM. Compared with other detection methods, the colorimetric method is simple, fast, and cheap and has a good development prospect. [ABSTRACT FROM AUTHOR]

Copper-based catalysts serve as the predominant methanol steam reforming material although several fundamental issues remain ambiguous such as the identity of active center and the aspects of reaction mechanism. Herein, we prepare Cu/Cu(Al)Ox catalysts with amorphous alumina-stabilized Cu2O adjoining Cu nanoparticle to provide Cu0−Cu+ sites. The optimized catalyst exhibits 99.5% CH3OH conversion with a corresponding H2 production rate of 110.8 μmol s−1 gcat−1 with stability over 300 h at 240 °C. A binary function correlation between the CH3OH reaction rate and surface concentrations of Cu0 and Cu+ is established based on kinetic studies. Intrinsic active sites in the catalyst are investigated with in situ spectroscopy characterization and theoretical calculations. Namely, we find that important oxygen-containing intermediates (CH3O* and HCOO*) adsorb at Cu0−Cu+ sites with a moderate adsorption strength, which promotes electron transfer from the catalyst to surface species and significantly reduces the reaction barrier of the C−H bond cleavage in CH3O* and HCOO* intermediates.Cu-based catalysts are widely considered to be effective materials for H2 production via methanol steam reforming. Herein, the authors explore a series of catalysts containing Cu0−Cu+ dual sites for facilitating C-H bond breaking and H2 evolution. [ABSTRACT FROM AUTHOR]

Neurotoxicity of organophosphate compounds (OPs) can catastrophically cause nervous system injury by inhibiting acetylcholinesterase (AChE) expression. Although artificial systems have been developed for indirect neuroprotection, they are limited to dissociating P-O bonds for eliminating OPs. However, these systems have failed to overcome the deactivation of AChE. Herein, we report our finding that Al3+ is engineered onto the nodes of metal–organic framework to synthesize MOF-808-Al with enhanced Lewis acidity. The resultant MOF-808-Al efficiently mimics the catalytic behavior of AChE and has a self-defense ability to break the activity inhibition by OPs. Mechanism investigations elucidate that Al3+ Lewis acid sites with a strong polarization effect unite the highly electronegative –OH groups to form the enzyme-like catalytic center, resulting in superior substrate activation and nucleophilic attack ability with a 2.7-fold activity improvement. The multifunctional MOF-808-Al, which has satisfactory biosafety, is efficient in reducing neurotoxic effects and preventing neuronal tissue damage. The neurotoxicity of organophosphate compounds damages nerve system by inhibiting acetylcholinesterase (AChE) expression, but it is difficult to overcome the deactivation of AChE. Here, the authors report the design of Lewis acid sites in metal-organic frameworks as AChE mimics for effective neuroprotection. [ABSTRACT FROM AUTHOR]

Electrooxidation of biomass platforms provides a sustainable route to produce valuable oxygenates, but the practical implementation is hampered by the severe carbon loss stemming from inherent instability of substrates and/or intermediates in alkaline electrolyte, especially under high concentration. Herein, based on the understanding of non-Faradaic degradation, we develop a single-pass continuous flow reactor (SPCFR) system with high ratio of electrode-area/electrolyte-volume, short duration time of substrates in the reactor, and separate feeding of substrate and alkaline solution, thus largely suppressing non-Faradaic degradation. By constructing a nine-stacked-modules SPCFR system, we achieve electrooxidation of glucose-to-formate and 5-hydroxymethylfurfural (HMF)-to-2,5-furandicarboxylic acid (FDCA) with high single-pass conversion efficiency (SPCE; 81.8% and 95.8%, respectively) and high selectivity (formate: 76.5%, FDCA: 96.9%) at high concentrations (formate: 562.8 mM, FDCA: 556.9 mM). Furthermore, we demonstrate continuous and kilogram-scale electrosynthesis of potassium diformate (0.7 kg) from wood and soybean oil, and FDCA (1.17 kg) from HMF. This work highlights the importance of understanding and suppressing non-Faradaic degradation, providing opportunities for scalable biomass upgrading using electrochemical technology. Electrooxidation of biomass provides a sustainable route to produce valuable chemicals, but suffers from non-Faradaic degradation in alkaline electrolysis at high reactant concentration. Here, the authors develop a single-pass continuous flow reactor to tackle this challenge, achieving kilogram-scale and continuous electrooxidation of glucose to formate and 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with high selectivity and high concentration. [ABSTRACT FROM AUTHOR]

The metal-support interaction (MSI) in heterogeneous catalysts plays a crucial role in reforming reaction to produce renewable hydrogen, but conventional objects are limited to single metal and support. Herein, we report a type of RhNi/TiO2 catalysts with tunable RhNi-TiO2 strong bimetal-support interaction (SBMSI) derived from structure topological transformation of RhNiTi-layered double hydroxides (RhNiTi-LDHs) precursors. The resulting 0.5RhNi/TiO2 catalyst (with 0.5 wt.% Rh) exhibits extraordinary catalytic performance toward ethanol steam reforming (ESR) reaction with a H2 yield of 61.7%, a H2 production rate of 12.2 L h−1 gcat−1 and a high operational stability (300 h), which is preponderant to the state-of-the-art catalysts. By virtue of synergistic catalysis of multifunctional interface structure (Rh-Niδ−-Ov-Ti3+; Ov denotes oxygen vacancy), the generation of formate intermediate (the rate-determining step in ESR reaction) from steam reforming of CO and CHx is significantly promoted on 0.5RhNi/TiO2 catalyst, accounting for its ultra-high H2 production. Ethanol steam reforming (ESR) reaction is an environmentally benign and sustainable route for H2 production. Herein, the authors demonstrate a conceptional strategy for rational design and preparation of highly-efficient catalyst toward ESR via an RhNi-TiO2 strong bimetal-support interaction. [ABSTRACT FROM AUTHOR]

Amorphous nano-metal catalysts often exhibit appealing catalytic properties, because the intrinsic linear scaling relationship can be broken. However, accurate control synthesis of amorphous nano-metal catalysts with desired size and morphology is a challenge. In this work, we discover that Cu(0) could be oxidized to amorphous CuxO species by supercritical CO2. The formation process of the amorphous CuxO is elucidated with the aid of machine learning. Based on this finding, a method to prepare Cu nanoparticles with an amorphous shell is proposed by supercritical CO2 treatment followed by electroreduction. The unique feature of this method is that the size of the particles with amorphous shell can be easily controlled because their size depends on that of the original crystal Cu nanoparticles. Moreover, the thickness of the amorphous shell can be easily controlled by CO2 pressure and/or treatment time. The obtained amorphous Cu shell exhibits high selectivity for C2+ products with the Faradaic efficiency of 84% and current density of 320 mA cm−2. Especially, the FE of C2+ oxygenates can reach up to 65.3 %, which is different obviously from the crystalline Cu catalysts. Amorphous metal catalysts often exhibit appealing catalytic properties, however, accurate control synthesis of amorphous nano-metal catalysts is a challenge. Here, the authors report a feasible strategy to prepare the amorphous Cu catalysts by supercritical CO2 treatment followed by electroreduction. The resulted catalyst shows high selectivity towards multi-carbon products for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Ancestral metabolism has remained controversial due to a lack of evidence beyond sequence-based reconstructions. Although prebiotic chemists have provided hints that metabolism might originate from non-enzymatic protometabolic pathways, gaps between ancestral reconstruction and prebiotic processes mean there is much that is still unknown. Here, we apply proteome-wide 3D structure predictions and comparisons to investigate ancestorial metabolism of ancient bacteria and archaea, to provide information beyond sequence as a bridge to the prebiotic processes. We compare representative bacterial and archaeal strains, which reveal surprisingly similar physiological and metabolic characteristics via microbiological and biophysical experiments. Pairwise comparison of protein structures identify the conserved metabolic modules in bacteria and archaea, despite interference from overly variable sequences. The conserved modules (for example, middle of glycolysis, partial TCA, proton/sulfur respiration, building block biosynthesis) constitute the basic functions that possibly existed in the archaeal-bacterial common ancestor, which are remarkably consistent with the experimentally confirmed protometabolic pathways. These structure-based findings provide a new perspective to reconstructing the ancestral metabolism and understanding its origin, which suggests high-throughput protein 3D structure prediction is a promising approach, deserving broader application in future ancestral exploration. Previous studies have reconstructed ancestral metabolism using sequence-based approaches. This study uses a high-throughput version of AlphaFold2 to compare proteome-wide 3D structure predictions of two representative strains of ancient archaea and bacteria. [ABSTRACT FROM AUTHOR]

Considerable attention has been drawn to tune the geometric and electronic structure of interfacial catalysts via modulating strong metal-support interactions (SMSI). Herein, we report the construction of a series of TiO2−x/Ni catalysts, where disordered TiO2−x overlayers immobilized onto the surface of Ni nanoparticles (~20 nm) are successfully engineered with SMSI effect. The optimal TiO2−x/Ni catalyst shows a CO conversion of ~19.8% in Fischer–Tropsch synthesis (FTS) process under atmospheric pressure at 220 °C. More importantly, ~64.6% of the product is C2+ paraffins, which is in sharp contrast to the result of the conventional Ni catalyst with the main product being methane. A combination study of advanced electron microscopy, multiple in-situ spectroscopic characterizations, and density functional theory calculations indicates the presence of Niδ−/TiO2−x interfacial sites, which could bind carbon atom strongly, inhibit methane formation and facilitate the C-C chain propagation, lead to the production of C2+ hydrocarbon on Ni surface. Considerable attention has been drawn to tune the geometric and electronic structure of interfacial catalysts via modulating strong metal-support interactions (SMSI). Here the authors report the remarkable catalytic performance of CO hydrogenation over an interfacial TiO2−x/Ni catalyst by means of SMSI. [ABSTRACT FROM AUTHOR]

Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production. However, the corresponding current density is very low at moderate cell potential that substantially limits the overall productivity. Here we report the electrooxidation of benzyl alcohol coupled with H2 production at high current density (540 mA cm−2 at 1.5 V vs. RHE) over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH). The absolute current can further reach 4.8 A at 2.0 V in a more realistic two-electrode membrane-free flow electrolyzer. Experimental combined with theoretical results indicate that the benzyl alcohol can be enriched at Au/CoOOH interface and oxidized by the electrophilic oxygen species (OH*) generated on CoOOH, leading to higher activity than pure Au. Based on the finding that the catalyst can be reversibly oxidized/reduced at anodic potential/open circuit, we design an intermittent potential (IP) strategy for long-term alcohol electrooxidation that achieves high current density (>250 mA cm−2) over 24 h with promoted productivity and decreased energy consumption. Electrochemical alcohol oxidation offers a promising approach to produce valuable chemicals that can be paired with fuel-producing reactions. Here, authors utilize gold and cobalt oxyhydroxide nanomaterials to obtain industrially-relevant electrolyzer current densities for benzyl alcohol oxidation. [ABSTRACT FROM AUTHOR]

The selective oxidation of glycerol to glyceric acid, an important value-added reaction from polyols, is a typical cascade catalytic process. It is still of great challenge to simultaneously achieve high glycerol activity and glyceric acid selectivity, suffering from either deep oxidation and C-C cleavage or poor oxidation efficiency from glyceraldehyde to glyceric acid. Herein, this work, inspired by nature, proposes a cascade synergistic catalysis strategy by atomic and low-coordinated cluster Pt on well-defined Cu-CuZrOx, which involves enhanced C-H activation on atomic Pt1 and O-H activation on cluster Ptn in the oxidation of glycerol to glyceraldehyde, and cluster Ptn for C=O activation followed by O-H insertion and atomic Pt1 for C-H activation in the tandem oxidation of glyceraldehyde to glyceric acid. The enhanced C-H activation in the cascade process by atomic Pt1 is revealed to be essential for the high glycerol activity (90.0±0.1%) and the glyceric acid selectivity (80.2±0.2%). The selective oxidation of glycerol to glyceric acid is an important value-added cascade catalytic process. Here the authors report a cascade synergistic catalysis strategy by atomic and low-coordinated cluster Pt on well-defined Cu-CuZrOx to simultaneously achieve high activity and selectivity. [ABSTRACT FROM AUTHOR]

Simultaneously increasing the activity and stability of the single-atom active sites of M–N–C catalysts is critical but remains a great challenge. Here, we report an Fe–N–C catalyst with nitrogen-coordinated iron clusters and closely surrounding Fe–N4 active sites for oxygen reduction reaction in acidic fuel cells. A strong electronic interaction is built between iron clusters and satellite Fe–N4 due to unblocked electron transfer pathways and very short interacting distances. The iron clusters optimize the adsorption strength of oxygen reduction intermediates on Fe–N4 and also shorten the bond amplitude of Fe–N4 with incoherent vibrations. As a result, both the activity and stability of Fe–N4 sites are increased by about 60% in terms of turnover frequency and demetalation resistance. This work shows the great potential of strong electronic interactions between multiphase metal species for improvements of single-atom catalysts. It is challenging to break the activity–stability trade-off in Fe–N–C fuel cell catalysts. Here, the authors show that interactions between iron atoms and clusters accelerate reaction kinetics and suppress demetalation to improve fuel cell stability. [ABSTRACT FROM AUTHOR]

Selective oxidation of ammonia to nitric oxide over platinum-group metal alloy gauzes is the crucial step for nitric acid production, a century-old yet greenhouse gas and capital intensive process. Therefore, developing alternative ammonia oxidation technologies with low environmental impacts and reduced catalyst cost are of significant importance. Herein, we propose and demonstrate a chemical looping ammonia oxidation catalyst and process to replace the costly noble metal catalysts and to reduce greenhouse gas emission. The proposed process exhibit near complete NH3 conversion and exceptional NO selectivity with negligible N2O production, using nonprecious V2O5 redox catalyst at 650 oC. Operando spectroscopy techniques and density functional theory calculations point towards a modified, temporally separated Mars-van Krevelen mechanism featuring a reversible V5+/V4+ redox cycle. The V = O sites are suggested to be the catalytically active center leading to the formation of the oxidation products. Meanwhile, both V = O and doubly coordinated oxygen participate in the hydrogen transfer process. The outstanding performance originates from the low activation energies for the successive hydrogen abstraction, facile NO formation as well as the easy regeneration of V = O species. Our results highlight a transformational process in extending the chemical looping strategy to producing base chemicals in a sustainable and cost-effective manner. This study reports a fundamentally new and commercially promising chemical looping ammonia oxidation scheme using an inexpensive transition metal oxide, and provides mechanistic insight into the oxygen species governing ammonia oxidation. [ABSTRACT FROM AUTHOR]

More than a decade of research on the electrocaloric (EC) effect has resulted in EC materials and EC multilayer chips that satisfy a minimum EC temperature change of 5 K required for caloric heat pumps1–3. However, these EC temperature changes are generated through the application of high electric fields4–8 (close to their dielectric breakdown strengths), which result in rapid degradation and fatigue of EC performance. Here we report a class of EC polymer that exhibits an EC entropy change of 37.5 J kg−1 K−1 and a temperature change of 7.5 K under 50 MV m−1, a 275% enhancement over the state-of-the-art EC polymers under the same field strength. We show that converting a small number of the chlorofluoroethylene groups in poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer into covalent double bonds markedly increases the number of the polar entities and enhances the polar–nonpolar interfacial areas of the polymer. The polar phases in the polymer adopt a loosely correlated, high-entropy state with a low energy barrier for electric-field-induced switching. The polymer maintains performance for more than one million cycles at the low fields necessary for practical EC cooling applications, suggesting that this strategy may yield materials suitable for use in caloric heat pumps.A study reports and characterizes a high-entropy electrocaloric polymer that switches under low fields, and discusses its potential suitability for use in caloric heat pumps. [ABSTRACT FROM AUTHOR]

Uncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N4 structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H2O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A gmetal−1 and a large turnover frequency of 5110 h−1 at a low overpotential of 216 mV (10 mA cm−2), 480–510 times larger than those of the commercial IrO2. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium. Uncovering the dynamics of active sites in the working conditions is important yet challenging. Here the authors identify dynamic-coupling oxygen on atomically dispersed iridium sites during oxygen evolution reaction using in situ techniques. [ABSTRACT FROM AUTHOR]

Plastic wastes represent a largely untapped resource for manufacturing chemicals and fuels, particularly considering their environmental and biological threats. Here we report electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to valuable commodity chemicals (potassium diformate and terephthalic acid) and H2 fuel. Preliminary techno-economic analysis suggests the profitability of this process when the ethylene glycol (EG) component of PET is selectively electrooxidized to formate (>80% selectivity) at high current density (>100 mA cm−2). A nickel-modified cobalt phosphide (CoNi0.25P) electrocatalyst is developed to achieve a current density of 500 mA cm−2 at 1.8 V in a membrane-electrode assembly reactor with >80% of Faradaic efficiency and selectivity to formate. Detailed characterizations reveal the in-situ evolution of CoNi0.25P catalyst into a low-crystalline metal oxy(hydroxide) as an active state during EG oxidation, which might be responsible for its advantageous performances. This work demonstrates a sustainable way to implement waste PET upcycling to value-added products. Plastic upcycling to value-added products is of great interests. Here the authors investigate a nickel-cobalt phosphide electrocatalyst for electroreforming of polyethylene terephthalate plastic toward valuable potassium diformate, terephthalic acid, and H2 fuel. [ABSTRACT FROM AUTHOR]

Benzene is a widely used commodity chemical, which is currently produced from fossil resources. Lignin, a waste from lignocellulosic biomass industry, is the most abundant renewable source of benzene ring in nature. Efficient production of benzene from lignin, which requires total transformation of Csp2-Csp3/Csp2-O into C-H bonds without side hydrogenation, is of great importance, but has not been realized. Here, we report that high-silica HY zeolite supported RuW alloy catalyst enables in situ refining of lignin, exclusively to benzene via coupling Bronsted acid catalyzed transformation of the Csp2-Csp3 bonds on the local structure of lignin molecule and RuW catalyzed hydrogenolysis of the Csp2-O bonds using the locally abstracted hydrogen from lignin molecule, affording a benzene yield of 18.8% on lignin weight basis in water system. The reaction mechanism is elucidated in detail by combination of control experiments and density functional theory calculations. The high-performance protocol can be readily scaled up to produce 8.5 g of benzene product from 50.0 g lignin without any saturation byproducts. This work opens the way to produce benzene using lignin as the feedstock efficiently. Efficient production of benzene from lignin is attractive and of great importance, but has not been realized. Here, the authors develop a strategy to transform lignin into benzene over a RuW/zeolite catalyst in water, and the yield of benzene can be as high as 18.8% on lignin weight basis. [ABSTRACT FROM AUTHOR]

Identifying the structure of iodoplumbate complexes in various solutions is essential for linking the coordination environment of the perovskite precursor to its final properties. In this study, we investigate the structure of methylammonium lead iodide (MAPbI3) perovskite precursor solutions as a function of the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide (DMSO) using X-ray absorption fine structure spectroscopy. It was demonstrated that DMSO modifies the precursor structure at the atomic level. X-ray diffraction, scanning electron microscopy, and UV–Vis spectroscopy analyses showed that the coordination environment of iodoplumbate complexes in precursor solutions is strongly correlated with the morphology of perovskite films. The appropriate amount of DMSO in the precursor solution modifies the Pb-O and Pb-I coordination of iodoplumbate complexes, which could change the growth process of high-crystallization perovskite films. This study sheds light on the formation mechanism of perovskite films from precursor solutions, which will lead to the development of high-quality films and ultimately high-efficiency devices. [ABSTRACT FROM AUTHOR]

Natural enzymes exhibit unparalleled selectivity due to the microenvironment around the active sites, but how to design artificial catalysts to achieve similar performance is a formidable challenge for the catalysis community. Herein, we report that a less selective platinum catalyst becomes highly active and selective for industrially relevant hydrosilylation of a broad range of substrates when a porous cage ligand is used for confinement around the catalytic active site. The catalyst is more than ten times more active than Karstedt's catalyst while being recyclable. Properties such as size-selective catalysis and Michaelis-Menten kinetics support the proposed enzyme-like model. This biomimetic catalyst exhibits remarkable site-selectivity through the cage's confining effect, which amplifies small steric differences into dramatic reactivity changes for similar functional groups within a molecule. Design of artificial catalysts to mimic enzyme activity and selectivity is a challenge in the catalysis field. Here, the authors design a platinum catalyst with a porous cage ligand which shows enzyme-like properties, such as high hydrosilylation activity and substrate size selectivity, while being recyclable. [ABSTRACT FROM AUTHOR]

Atomic interface regulation is thought to be an efficient method to adjust the performance of single atom catalysts. Herein, a practical strategy was reported to rationally design single copper atoms coordinated with both sulfur and nitrogen atoms in metal-organic framework derived hierarchically porous carbon (S-Cu-ISA/SNC). The atomic interface configuration of the copper site in S-Cu-ISA/SNC is detected to be an unsymmetrically arranged Cu-S1N3 moiety. The catalyst exhibits excellent oxygen reduction reaction activity with a half-wave potential of 0.918 V vs. RHE. Additionally, through in situ X-ray absorption fine structure tests, we discover that the low-valent Cuprous-S1N3 moiety acts as an active center during the oxygen reduction process. Our discovery provides a universal scheme for the controllable synthesis and performance regulation of single metal atom catalysts toward energy applications. Engineering the coordination environment of single atom catalysts offers to opportunity to optimize electrocatalytic activity. In this work, the authors prepare an unsymmetrical Cu-S1N3 single atom site on porous carbon with high performance in the oxygen reduction reaction. [ABSTRACT FROM AUTHOR]

H9N2 avian influenza virus has spread worldwide, and vaccination with an inactivated virus is currently the major prevention method in China. To further understand the effect of the selection pressure from antibodies on the evolution of H9N2 avian influenza virus, F/98 (A/Chicken/Shanghai/F/98), which is the vaccine representative of H9N2 avian influenza virus in East China, was used for serial passaging for 20 generations in chickens with and without vaccination. After plaque purification from trachea and lung tissues, 390 quasispecies were obtained. The second-generation quasispecies under the selection pressure of vaccine antibodies had undergone 100% antigen variation, while after passaging to the fifth generation, only 30–40% of the quasispecies displayed antigen variation when there was no selection pressure of vaccine antibodies, implying that the selection pressure of vaccine antibodies promotes the antigen variation of F/98. We found for the first time that there were three mutation hotspots in the HA genes of the quasispecies under the selection pressure of vaccine antibodies, which were K131R, A168T, and N201D. Moreover, under the selection pressure of vaccine antibodies, 10 amino acids (67–76) of the NA protein of all quasispecies were deleted, and PB2 of the quasispecies had undergone a high-frequency R355K mutation. However, without selection pressure of vaccine antibodies, NP had undergone two high-frequency mutations, namely, V186I and L466I, and a high-frequency mutation of L77I appeared in the NS gene. This result shows that the vaccine antibody selection pressure could control and regulate gene variation of the F/98 virus. Compared to that of the parental virus F/98, the EID50 of the twentieth passaged virus under the selection pressure of vaccine antibodies did not change, while the EID50 of the twentieth passaged virus without selection pressure of vaccine antibodies was significantly enhanced by 794 times. Furthermore, the twentieth passaged virus with selection pressure from vaccine antibodies lost its lethal ability in embryonated chicken eggs, whereas the EID50 of the twentieth passaged virus without selection pressure of vaccine antibodies increased to 6.3 times that of the F/98 strain. All the above results show that the selection pressure of vaccine antibodies promotes the antigen variation of H9N2 avian influenza virus and plays a role in regulating and controlling gene mutation of H9N2 avian influenza virus. [ABSTRACT FROM AUTHOR]

The production of 2D metal-organic frameworks (MOFs) with highly exposed active surfaces is of great importance for catalysis. Here we demonstrate the formation of MOF nanosheets by utilizing CO2 as a capping agent to control the oriented growth of MOF. This strategy has many advantages over the conventional methods. For example, it is template-free and proceeds at mild temperature (35 °C), CO2 can be easily removed by depressurization, and the properties of the MOF nanosheets can be well adjusted by changing CO2 pressure. Such a simple, rapid, efficient and adjustable route produces MOF nanosheets with ultrathin thickness (∼10 nm), small lateral size (∼100 nm) and abundant unsaturated coordination metal sites on surfaces. Owing to these unique features, the as-synthesized MOF nanosheets exhibit superior activity for catalyzing the oxidation reactions of alcohols. Producing two-dimensional metal-organic frameworks (MOFs) with highly exposed active surfaces is important for catalysis. Here, authors prepare MOF nanosheets by using CO2 as a capping agent to control the oriented growth of MOFs. [ABSTRACT FROM AUTHOR]

The industrial synthesis of ammonia (NH3) using iron-based Haber-Bosch catalyst requires harsh reaction conditions. Developing advanced catalysts that perform well at mild conditions (<400 °C, <2 MPa) for industrial application is a long-term goal. Here we report a Co-N-C catalyst with high NH3 synthesis rate that simultaneously exhibits dynamic and steady-state active sites. Our studies demonstrate that the atomically dispersed cobalt weakly coordinated with pyridine N reacts with surface H2 to produce NH3 via a chemical looping pathway. Pyrrolic N serves as an anchor to stabilize the single cobalt atom in the form of Co1-N3.5 that facilitates N2 adsorption and step-by-step hydrogenation of N2 to *HNNH, *NH-NH3 and *NH2-NH4. Finally, NH3 is facilely generated via the breaking of the *NH2-NH4 bond. With the co-existence of dynamic and steady-state single atom active sites, the Co-N-C catalyst circumvents the bottleneck of N2 dissociation, making the synthesis of NH3 at mild conditions possible. The industrial synthesis of ammonia using iron-based Haber-Bosch catalyst requires harsh reaction conditions. Here the authors show co-existence of dynamic and steady-state single atom active sites over Co-N-C catalyst to facilitate nitrogen activation for ammonia synthesis under mild conditions. [ABSTRACT FROM AUTHOR]

Highlights: Precisely located S doping of atomic Fe-N4 in Fe(N3)(N–C–S) motif was realized. This S doping renders weakened *OH binding and faster charge transfer on Fe-N4. Fe-NSC showed excellent oxygen reduction reaction performance with onset potential ~ 1.09 V and half-wave potential ~ 0.92 V.Immobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety. [ABSTRACT FROM AUTHOR]

Selective hydrogenolysis of biomass-derived glycerol to propanediol is an important reaction to produce high value-added chemicals but remains a big challenge. Herein we report a PtCu single atom alloy (SAA) catalyst with single Pt atom dispersed on Cu nanoclusters, which exhibits dramatically boosted catalytic performance (yield: 98.8%) towards glycerol hydrogenolysis to 1,2-propanediol. Remarkably, the turnover frequency reaches up to 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1, which is to our knowledge the largest value among reported heterogeneous metal catalysts. Both in situ experimental studies and theoretical calculations verify interface sites of PtCu–SAA serve as intrinsic active sites, in which the single Pt atom facilitates the breakage of central C–H bond whilst the terminal C–O bond undergoes dissociation adsorption on adjacent Cu atom. This interfacial synergistic catalysis based on PtCu–SAA changes the reaction pathway with a decreased activation energy, which can be extended to other noble metal alloy systems. Selective hydrogenolysis of biomass glycerol to propanediol is a promising route for the production of high-value chemicals but remains a challenge. Here, the authors find a PtCu single atom alloy catalyst exhibits remarkably boosted performance with a turnover frequency value of 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1. [ABSTRACT FROM AUTHOR]

Supported gold catalysts play a crucial role in the chemical industry; however, their poor on-stream stability because of the sintering of the gold nanoparticles restricts their practical application. The strong metal-support interaction (SMSI), an important concept in heterogeneous catalysis, may be applied to construct the structure of catalysts and, hence, improve their reactivity and stability. Here we report an ultrastable Au nanocatalyst after calcination at 800 °C, in which Au nanoparticles are encapsulated by a permeable TiOx thin layer induced by melamine under oxidative atmosphere. Owning to the formed TiOx overlayer, the resulting Au catalyst is resistant to sintering and exhibits excellent activity and stability for catalytic CO oxidation. Furthermore, this special strategy can be extended to colloidal Au nanoparticles supported on TiO2 and commercial gold catalyst denoted as RR2Ti, providing a universal way to engineer and develop highly stable supported Au catalysts with tunable activity. Sintering-resistant Au nanoparticles are highly desirable due to their low Tammann temperature. Here, the authors report an ultrastable titania-supported Au nanocatalyst through an encapsulation strategy under oxidative atmosphere. [ABSTRACT FROM AUTHOR]

Designing active sites and engineering electronic properties of heterogeneous catalysts are both promising strategies that can be employed to enhance the catalytic activity for CO2 hydrogenation. Herein, we report RhCo porous nanospheres with a high density of accessible grain boundaries as active sites for improved catalytic performance in the hydrogenation of CO2 to methanol. The porous nanosphere morphological feature allows for a high population of grain boundaries to be accessible to the reactants, thereby providing sufficient active sites for the catalytic reaction. Moreover, in-situ X-ray photoelectron spectroscope (XPS) results revealed the creation of negatively charged Rh surface atoms that promoted the activation of CO2 to generate CO2δ- and methoxy intermediates. The obtained RhCo porous nanospheres exhibited remarkable low-temperature catalytic activity with a turnover frequency (TOFRh) of 612 h-1, which was 6.1 and 2.5 times higher than that of Rh/C and RhCo nanoparticles, respectively. This work not only develops an efficient catalyst for CO2 hydrogenation, but also demonstrates a potential approach for the modulation of active sites and electronic properties. [ABSTRACT FROM AUTHOR]

Mass customization (MC) under the context of the Internet of Things (IoT) is expected to reform the traditional mass manufacturing. To contribute to MC from information communication and user interaction aspects, this work proposes an Ultra-High Frequency (UHF) RFID tag with an Impulse-Radio Ultra-Wide Band (IR-UWB) transmitter and an inkjet-printed Electrochromic (EC) display. First, compared to the conventional UHF RFID tags, the proposed tag shows the advantage of higher transmission data rate with still low power consumption. The response time in multi-tag accessing scenarios can be reduced to less than 500 ms per 1000 tags by the pipeline of the tag responses in IR-UWB link and the reader acknowledgments in UHF RFID link as well as by reducing the length of empty slots. Second, the tag is integrated with a flexible EC display manufactured by inkjet-printing on the polyimide substrate. It works as an automatically refreshed paper label that offers an intuitive human-to-device interface to improve the efficiency of the offline workers. To conquer the material variations and make use of the long retention time of the printed EC display, its threshold voltage is utilized and a feedback comparator enabling the display driver by the threshold voltage is designed. A System-on-Chip (SoC) is implemented in UMC 0.18 μm CMOS process. According to the experimental results: 1) the IR-UWB transmitter achieves 1.02 V pulse amplitude and 900 ps pulse duration with 18 pJ/pulse energy consumption; 2) the EC display driver automatically refreshes the display when the image fades out, and consumes 1.98 μW per 1 cm display size to retain an image. The UHF/UWB RFID display tag integrated on polyimide substrate is conceptually demonstrated at the end of the paper. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) have been widely used as catalysts owing to their tunable structure and atomic dispersion of high-valence metal ions; however, limited tunability of electronic structure and valence states have hindered further improvement in their catalytic performance. Herein, we reduced ultrathin LDH precursors in situ and topotactically converted them to atomically thick (~2 nm) two-dimensional (2D) multi-metallic, single crystalline alloy nanosheets with highly tunable metallic compositions. The as-obtained alloy nanosheets not only maintained the vertically aligned ultrathin 2D structure, but also inherited the atomic dispersion of the minor metallic compositions of the LDH precursors, even though the atomic percentage was higher than 20%, which is far beyond the reported percentages for single-atom dispersions (usually less than 0.1%). Besides, surface engineering of the alloy nanosheets can finely tune the surface electronic structure for catalytic applications. Such in situ topotactic conversion strategy has introduced a novel approach for atomically dispersed alloy nanostructures and reinforced the synthetic methodology for ultrathin 2D metal-based catalysts. [ABSTRACT FROM AUTHOR]

We designed and prepared a hetero-dimensional hybrid (HDH) based on molybdenum selenide (MoSe) nanodots (NDs) anchored in few-layer MoSe nanosheets (NSs) (MoSe HDH) via a one-pot hydrothermal process. The MoSe HDH exhibits excellent electrocatalytic activity toward hydrogen evolution reaction (HER). This is because, on the one hand, the edge-abundant features of MoSe NDs and the unique defect-rich structure at the interface of MoSe NSs/NDs could bring in more active sites for HER; on the other hand, the random stacking of the flake-like MoSe NSs on the surface of the supporting electrode may achieve efficient charge transport. Additionally, the MoSe HDH shows good water stability, desirable biocompatibility, and high near infrared (NIR) photothermal conversion efficiency. Therefore, the MoSe HDH is investigated as a nanomedicine in NIR photothermal therapy (PTT) for cancer. Specifically, the MoSe HDH can be applied as a dual-modal probe for computed tomography (CT) and photoacoustic tomography (PA) imaging owing to its strong X-ray attenuation ability and NIR absorption. Therefore, the MoSe HDH, combining PTT with CT/PA imaging into one system, holds great potential for imaging-guided cancer theranostics. This work may provide an ingenious strategy to prepare other hetero-dimensional layered transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

Correction to: I Nature Communications i https://doi.org/10.1038/s41467-018-07850-2, published online 21 December 2018. These authors contributed equally: Yuanjun Chen, Shufang Ji, Shu Zhao. [Extracted from the article]

The revolution of Internet-of-Things (IoT) is reshaping the modern food supply chains with promising business prospects. To be successful in practice, the IoT solutions should create 'income-centric' values beyond the conventional 'traceability-centric' values. To accomplish what we promised to users, sensor portfolios and information fusion must correspond to the new requirements introduced by this income-centric value creation. In this paper, we propose a value-centric business-technology joint design framework. Based on it the income-centric added-values including shelf life prediction, sales premium, precision agriculture, and reduction of assurance cost are identified and assessed. Then corresponding sensor portfolios are developed and implemented. Three-tier information fusion architecture is proposed as well as examples about acceleration data processing, self-learning shelf life prediction and real-time supply chain re-planning. The feasibilities of the proposed design framework and solution have been confirmed by the field trials and an implemented prototype system. [ABSTRACT FROM AUTHOR]

A combined analytical and numerical process has been developed to model and optimize thermoelements. In this way, the performance of commercial n- and p-type thermoelectric materials can be optimized to deliver the maximum output power and conversion efficiency. The validity of the method is demonstrated using a silicon germanium unicouple. [ABSTRACT FROM AUTHOR]

Developing effective catalysts based on earth abundant elements is critical for CO2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (jCO) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a jCO of 14.0 mA cm−2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher jCO of 29.7 mA cm−2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N3 site, which facilitates the formation of the key intermediate COOH* through a lowered free energy barrier. Developing effective catalysts based on earth abundant elements is critical for electrochemical CO2 reduction. Here, the authors prepare a manganese single atom catalyst with high CO2 reduction performance, which can be attributed to the Mn-N3 site embedded in graphitic carbon nitride. [ABSTRACT FROM AUTHOR]

The grand challenge in the development of atomically dispersed metallic catalysts is their low metal-atom loading density, uncontrollable localization and ambiguous interactions with supports, posing difficulty in maximizing their catalytic performance. Here, we achieve an interface catalyst consisting of atomic cobalt array covalently bound to distorted 1T MoS2 nanosheets (SA Co-D 1T MoS2). The phase of MoS2 transforming from 2H to D-1T, induced by strain from lattice mismatch and formation of Co-S covalent bond between Co and MoS2 during the assembly, is found to be essential to form the highly active single-atom array catalyst. SA Co-D 1T MoS2 achieves Pt-like activity toward HER and high long-term stability. Active-site blocking experiment together with density functional theory (DFT) calculations reveal that the superior catalytic behaviour is associated with an ensemble effect via the synergy of Co adatom and S of the D-1T MoS2 support by tuning hydrogen binding mode at the interface. While single-atom catalysis offers an efficient materials usage, the ambiguous interactions with supports poses a difficulty in understanding catalytic performances. Here, authors show an ensemble effect via synergy of Co adatoms and the S of MoS2 supports to boost hydrogen evolution activities. [ABSTRACT FROM AUTHOR]

Moiré superlattices (MSLs) are modulated structures produced from homogeneous or heterogeneous 2D layers stacked with a twist angle and/or lattice mismatch. Expanding the range of available materials, methods for fabricating MSL, and realization of unique emergent properties are key challenges. Here we report a facile bottom-up synthesis of homogeneous MSL based on a wide-gap 2D semiconductor, BiOCl, using a one-pot solvothermal approach with robust reproducibility. Unlike previous MSLs usually prepared by directly stacking two monolayers, our BiOCl MSLs are realized in a scalable, direct way through chemical growth of spiral-type nanosheets driven by screw-dislocations. We find emergent properties including large band gap reduction (∼0.6 eV), two-fold increase in carrier lifetime, and strongly enhanced photocatalytic activity. First-principles calculations reveal that such unusual properties can be ascribed to the locally enhanced inter-layer coupling associated with the Moiré potential modulation. Our results demonstrate the promise of MSL materials for chemical and physical functions. Expanding the range of available materials, methods for fabricating Moiré superlattices, and realization of new emergent properties are key challenges. Here the authors report a facile bottom-up synthesis of homogeneous Moiré superlattices based on a wide-gap 2D semiconductor, bismuth oxychloride. [ABSTRACT FROM AUTHOR]

Atomically dispersed metal-N-C structures are efficient active sites for catalyzing benzene oxidation reaction (BOR). However, the roles of N and C atoms are still unclear. We report a polymerization-regulated pyrolysis strategy for synthesizing single-atom Fe-based catalysts, and present a systematic study on the coordination effect of Fe-NxCy catalytic sites in BOR. The special coordination environment of single-atom Fe sites brings a surprising discovery: Fe atoms anchored by four-coordinating N atoms exhibit the highest BOR performance with benzene conversion of 78.4% and phenol selectivity of 100%. Upon replacing coordinated N atoms by one or two C atoms, the BOR activities decrease gradually. Theoretical calculations demonstrate the coordination pattern influences not only the structure and electronic features, but also the catalytic reaction pathway and the formation of key oxidative species. The increase of Fe-N coordination number facilitates the generation and activation of the crucial intermediate O=Fe=O species, thereby enhancing the BOR activity. Atomically dispersed metal-N-C are efficient active site for benzene oxidation but the roles of N and C atoms are still unclear. Here the authors report a highly-active single-atom Fe-based benzene oxidation catalyst and provide deep insights into the structure-activity relationship at atomic level. [ABSTRACT FROM AUTHOR]

Efficient electroreduction of carbon dioxide to multicarbon products in aqueous solution is of great importance and challenging. Unfortunately, the low efficiency of the production of C2 products limits implementation at scale. Here, we report reduction of carbon dioxide to C2 products (acetic acid and ethanol) over a 3D dendritic copper-cuprous oxide composite fabricated by in situ reduction of an electrodeposited copper complex. In potassium chloride aqueous electrolyte, the applied potential was as low as −0.4 V vs reversible hydrogen electrode, the overpotential is only 0.53 V (for acetic acid) and 0.48 V (for ethanol) with high C2 Faradaic efficiency of 80% and a current density of 11.5 mA cm−2. The outstanding performance of the electrode for producing the C2 products results mainly from near zero contacting resistance between the electrocatalysts and copper substrate, abundant exposed active sites in the 3D dendritic structure and suitable copper(I)/copper(0) ratio of the electrocatalysts. Electrocatalytic reduction of carbon dioxide is attractive for obtaining multicarbon products, but conversion efficiency is low. Here the authors use copper complex materials for electrochemical reduction of carbon dioxide to ethanol and acetic acid with high efficiencies and activities. [ABSTRACT FROM AUTHOR]

Noble metals play a momentous role in heterogeneous catalysis but still face a huge challenge in selectivity control. Herein, we report isolating contiguous Pt atoms and forming Pt-Zn intermetallic nanoparticles as an effective strategy to optimize the selectivity of Pt catalysts. Contiguous Pt atoms are isolated into single atoms and Pt-Zn intermetallic nanoparticles are formed which are supported on hollow nitrogen-doped carbon nanotubes (PtZn/HNCNT), as confirmed by aberration-corrected high-resolution transmission electron microscopy and X-ray absorption spectrometry measurements. Interestingly, this PtZn/HNCNT catalyst promotes the hydrogenation of 4-nitrophenylacetylene to 4-aminophenylacetylene with a much higher conversion (> 99%) and selectivity (99%) than the comparison samples with Pt isolated-single-atomic-sites (Pt/HNCNT) and Pt nanoparticles (Pt/CN). Further density functional theory (DFT) calculations disclose that the positive Zn atoms assist the adsorption of nitro group and Pt-Zn intermetallic nanoparticles facilitate the hydrogenation on nitro group kinetically. Noble metals play a momentous role in heterogeneous catalysis but still face a huge challenge in selectivity control. Herein, the authors demonstrate that isolating contiguous Pt atoms and forming Pt-Zn intermetallic nanoparticles is an effective strategy to optimize the selectivity of Pt catalysts. [ABSTRACT FROM AUTHOR]

Developing highly efficient electrocatalysts based on cheap and earth-abundant metals for CO2 reduction is of great importance. Here we demonstrate that the electrocatalytic activity of manganese-based heterogeneous catalyst can be significantly improved through halogen and nitrogen dual-coordination to modulate the electronic structure of manganese atom. Such an electrocatalyst for CO2 reduction exhibits a maximum CO faradaic efficiency of 97% and high current density of ~10 mA cm−2 at a low overpotential of 0.49 V. Moreover, the turnover frequency can reach 38347 h−1 at overpotential of 0.49 V, which is the highest among the reported heterogeneous electrocatalysts for CO2 reduction. In situ X-ray absorption experiment and density-functional theory calculation reveal the modified electronic structure of the active manganese site, on which the free energy barrier for intermediate formation is greatly reduced, thus resulting in a great improvement of CO2 reduction performance. While renewable CO2 conversion provides a means to remove and recycle waste emissions, there are few earth-abundant materials that are both efficient and active. Here, authors prepare N-doped carbon with atomic manganese as high-performance CO2 reduction electrocatalyst. [ABSTRACT FROM AUTHOR]

Optimising the supported modes of atom or ion dispersal onto substrates, to synchronously integrate high reactivity and robust stability in catalytic conversion, is an important yet challenging area of research. Here, theoretical calculations first show that three-coordinated copper (Cu) sites have higher activity than four-, two- and one-coordinated sites. A site-selective etching method is then introduced to prepare a stacked-nanosheet metal–organic framework (MOF, CASFZU-1)-based catalyst with precisely controlled coordination number sites on its surface. The turnover frequency value of CASFZU-1 with three-coordinated Cu sites, for cycloaddition reaction of CO2 with epoxides, greatly exceed those of other catalysts reported to date. Five successive catalytic cycles reveal the superior stability of CASFZU-1 in the stacked-nanosheet structure. This study could form a basis for the rational design and construction of highly efficient and robust catalysts in the field of single-atom or ion catalysis. Engineering the coordination mode of atom or ion onto the substrate remains challenging. Here, guided by theoretical calculation, the authors prepare stacked-nanosheet MOF based catalyst with precisely controlled coordination sites on the surface and enhanced catalytic reactivity and structural robustness. [ABSTRACT FROM AUTHOR]

Single atom catalyst, which contains isolated metal atoms singly dispersed on supports, has great potential for achieving high activity and selectivity in hetero-catalysis and electrocatalysis. However, the activity and stability of single atoms and their interaction with support still remains a mystery. Here we show a stable single atomic ruthenium catalyst anchoring on the surface of cobalt iron layered double hydroxides, which possesses a strong electronic coupling between ruthenium and layered double hydroxides. With 0.45 wt.% ruthenium loading, the catalyst exhibits outstanding activity with overpotential 198 mV at the current density of 10 mA cm−2 and a small Tafel slope of 39 mV dec−1 for oxygen evolution reaction. By using operando X-ray absorption spectroscopy, it is disclosed that the isolated single atom ruthenium was kept under the oxidation states of 4+ even at high overpotential due to synergetic electron coupling, which endow exceptional electrocatalytic activity and stability simultaneously. While water splitting offers a carbon-neutral means to store energy, water oxidation is sluggish and corrosive over earth-abundant electrocatalysts. Here, authors show single ruthenium atoms over cobalt-iron layered double hydroxides to be effective and stable oxygen evolution electrocatalysts. [ABSTRACT FROM AUTHOR]

Efficient, durable and inexpensive electrocatalysts that accelerate sluggish oxygen reduction reaction kinetics and achieve high-performance are highly desirable. Here we develop a strategy to fabricate a catalyst comprised of single iron atomic sites supported on a nitrogen, phosphorus and sulfur co-doped hollow carbon polyhedron from a metal-organic framework@polymer composite. The polymer-based coating facilitates the construction of a hollow structure via the Kirkendall effect and electronic modulation of an active metal center by long-range interaction with sulfur and phosphorus. Benefiting from structure functionalities and electronic control of a single-atom iron active center, the catalyst shows a remarkable performance with enhanced kinetics and activity for oxygen reduction in both alkaline and acid media. Moreover, the catalyst shows promise for substitution of expensive platinum to drive the cathodic oxygen reduction reaction in zinc-air batteries and hydrogen-air fuel cells. Development of fuel cells and metal-air batteries is hindered by electrocatalyst performance, which can be enhanced with uniform and atomically dispersed active sites. Here the authors report an iron-based electrocatalyst for oxygen reduction in cathodes for a zinc-air battery and a hydrogen-air fuel cell. [ABSTRACT FROM AUTHOR]

The flexible electronics has been deemed to be a promising approach to the wearable electronic systems. However, the mismatching between the existing flexible deices and the conventional computing paradigm results an impasse in this field. In this work, a new way to access to this goal is proposed by combining flexible devices and the neuromorphic architecture together. To achieve that, a high-performance flexible artificial synapse is created based on a carefully designed and optimized memristive transistor. The device exhibits high-performance which has near-linear non-volatile resistance change under 10,000 identical pulse signals within the 515% dynamic range, and has the energy consumption as low as 45 fJ per pulse. It also displays multiple synaptic plasticity features, which demonstrates its potential for real-time online learning. Besides, the adaptability by virtue of its three-terminal structure specifically contributes its improved uniformity, repeatability, and reduced power consumption. This work offers a very viable solution for the future wearable computing. Artificial synapses: memristive transistors with mechanical and synaptic flexibility Mechanically flexible artificial synapses based on memristive transistors demonstrate different kinds of synaptic plasticity. The synapse is a fundamental component in neuromorphic computing (a brain-inspired computing approach that aims to provide more efficient computing compared to conventional approaches). Yiqiang Zhan, Lirong Zheng, and Fernando Seoane with collaborators in Sweden and China now report an artificial synapse based on a memristive transistor that is mechanically flexible. Key to the design of their synapse is a three-terminal structure, which enables gate tuning. The ability to adjust the voltage on the gate terminal enables variations in the device to be compensated thereby improving performance uniformity and repeatability. The researchers also show that gate tuning can reduce the total energy consumption per spiking event to 45 fJ and demonstrate a variety of synaptic plastic features important for replicating neuromorphic behavior. [ABSTRACT FROM AUTHOR]

Development of single-site catalysts supported by ultrathin two-dimensional (2D) porous matrix with ultrahigh surface area is highly desired but also challenging. Here we report a cocoon silk chemistry strategy to synthesize isolated metal single-site catalysts embedded in ultrathin 2D porous N-doped carbon nanosheets (M-ISA/CNS, M = Fe, Co, Ni). X-ray absorption fine structure analysis and spherical aberration correction electron microscopy demonstrate an atomic dispersion of metal atoms on N-doped carbon matrix. In particular, the Co-ISA/CNS exhibit ultrahigh specific surface area (2105 m2 g−1) and high activity for C-H bond activation in the direct catalytic oxidation of benzene to phenol with hydrogen peroxide at room temperature, while the Co species in the form of phthalocyanine and metal nanoparticle show a negligible activity. Density functional theory calculations discover that the generated O = Co = O center intermediates on the single Co sites are responsible for the high activity of benzene oxidation to phenol. Single-site catalysts supported by ultrathin two-dimensional (2D) porous matrix are desirable for catalytic reactions, yet their synthesis remains a great challenge. Herein the authors report a cocoon silk chemistry strategy to synthesize isolated metal single-site catalysts embedded in ultrathin 2D porous N-doped carbon nanosheets. [ABSTRACT FROM AUTHOR]