Catalytic hydrodeoxygenation (HDO) serves as a crucial strategy for the valorization of lignin-derived oil into hydrocarbon fuels. Although earth-abundant transition-metal catalysts offer compelling economic advantages, their practical implementation in HDO is constrained by intrinsically inferior activity, necessitating harsh operating conditions. One way to overcome this limitation resides in the rational engineering the support to creating tailored active sites that synergistically couple with the metallic phase, thereby markedly enhancing HDO performance under milder conditions. In this study, nickel-based catalysts supported on amorphous silicaalumina (Ni/ASA) catalysts with tailoring Al content were synthesized. Precise modulation of Al content directly governs catalyst morphology, Ni dispersion, and acid site distribution. Among the series, Ni/ASA-1Al, featuring a large specific surface area, minimal Ni particle size, and maximum density of strong acid sites, exhibited optimal catalytic performance. Under optimized conditions (200 degrees C, 4 h, 1 MPa H2), complete guaiacol conversion was achieved with a cyclohexane yield of 93.3%. Moreover, Ni/ASA-1Al showed excellent versatility in the HDO of diverse phenolic monomers, dimers, and bio-oil. This work provides fundamental insights into the Al-mediated modulation of ASA-supported catalysts and establishes a scalable strategy for designing cost-effective catalysts for bio-oil upgrading.

The non-oxidative dehydrogenation of ethanol (EDH) to acetaldehyde represents a promising route for biomass resource utilization. Although Cu/ZnO catalysts are widely employed industrially, their application in EDH remains underexplored. This study investigates the impact of precursor composition-using aurichalcite, zinc malachite, and their mixtures-on the structure and EDH performance of derived Cu/ZnO catalysts. The precursor composition significantly modulates the oxygen vacancy concentration in the catalysts, thereby tuning electronic metal-support (Cu-ZnO) interactions and the relative abundances of Cu0 and defective Zn delta+ species. The aurichalcite-derived catalyst exhibits the smallest Cu particle size, highest oxygen vacancy and Cu0 content, facilitating the formation of abundant oxygen vacancy-Cu0 dual-active-sites at the Cu-ZnO interface. In situ DRIFTS characterization demonstrate that oxygen vacancies play a critical role in the adsorption of ethanol, and the oxygen vacancy-Cu0 dual-active sites facilitate the cleavage of the alpha-C-H bond, thereby enhancing the rate of ethanol dehydrogenation. Mechanism studies reveal that the oxygen vacancy promotes adsorption via the ethanol C-O or O-H bond, while adjacent metallic Cu0&Cu+ activates and cleaves the C-H and O-H bonds. This oxygen vacancy-metal dual-active-sites synergistically enhances the intrinsic activity for ethanol dehydrogenation. Furthermore, catalyst with lower acidity and basicity were found to favor acetaldehyde selectivity. The catalyst derived from the mixed-phase precursor demonstrated optimal performance, achieving 63 % ethanol conversion and 90.2 % acetaldehyde selectivity at 270 degrees C under a WHSV of 1 h- 1, with a catalyst lifetime exceeding 230 h. This work provides valuable insights for designing efficient Cu/ZnO catalysts for selective acetaldehyde production via ethanol dehydrogenation.

The spinel-type MnFe2O4 catalyst exhibits excellent performance for selective catalytic reduction (SCR) of NOX by NH3, yet the catalytic mechanism remains to be established. Herein, density functional theory (DFT) calculations were performed to unveil the active sites and molecular-level NH3-SCR reaction mechanism of the MnFe2O4 catalyst. The results indicate that the key reactants and products are chemically adsorbed on the MnFe2O4(100) surface. The surface 2-fold coordinated Mn atom is identified as the key active center for NH3 and NO adsorption, which plays an important role in initiating the SCR reaction. The NH2* species, generated from the first dehydrogenation of NH3, serves as a vital intermediate. Its further dehydrogenation is hindered by a very high energy barrier (323.03 kJ mol-1). Mechanistic analysis shows that the main reaction channel for NH3-SCR over the MnFe2O4 catalyst includes two steps: (1) NH2 production from NH3 dehydrogenation and (2) NH2-NO reaction. The NH2-NO reaction is the rate-limiting step due to its relatively higher energy barrier (121.56 kJ mol-1). The MnFe2O4 catalyst has a superior N2 selectivity because the energy barrier of N2O production is much higher than that of N2 production. This work not only advances the understanding of denitration at the molecular scale but also offers a theoretical basis for the rational design of efficient catalysts for NH3-SCR.

Ru/Nb2O5 is effective for furfural aqueous reductive conversion. Systematic characterization, kinetic studies and in situ DRIFT tests demonstrated that the Ru delta+ species abundance is highly correlated with the adsorption behavior of the substrate, key intermediate and product (furfural, 2-cyclopentenone, and cyclopentanone), which governs the FFR conversion rate and cyclopentanoid product selectivity.

Controlling both the hydrogenation performance and the activation of Schiff base intermediate in catalysts is crucial for attaining high slectivity toward primary amine in the reduction amination of furfural. However, it remains pending for Pt-based catalysts, on which the reduction amination reactions rarely generate primary amines so far. In this work, we developed a Pt/TiO2 nanocluster (NC) catalyst with a size distribution independent of the reduction temperature and loading amount. The reductive amination performance was investigated by regulating the surface electronic state and the distance between Pt NCs, and the results, attractively, revealed that the catalyst with a lower loading amount exhibited a higher furfurylamine (FAM) yield. Further studies unraveled that the catalyst with a larger Pt NC proximity had more abundant effective adsorption sites for the key intermediate Schiff base, i.e., the surface Ti4+ sites adjacent to the Pt NC, promoting the transformation of the Schiff base. Meanwhile, reducing the surface density of Pt NCs helped control the intensity of hydrogen spillover, thereby inhibiting the occurrence of overhydrogenation reactions. Optimal activity for primary amine generation from furfural reductive amination was achieved with a Pt NC catalyst reduced at 500 degrees C and with a loading amount of only 0.1 wt %, resulting in a FAM yield exceeding 93% and a production rate of 297.9 gFAM gPt h-1. The reaction mechanism, involving the competitive relationship between NH3 and H2, was elucidated through kinetic studies and theoretical calculations. This work provides insights for the designation of catalysts with controllable hydrogenation activity and adsorption selectivity and contributes to the understanding of the mechanism of the reductive amination reaction.

Strong metal-support interaction (SMSI) is one of the most important phenomena in the history of heterogeneous catalysis and has gained renewed attention in the past decade due to the emergence of various new types of SMSI. However, the origin of SMSI still remains in debate. Both minimizing surface energy and electron transfer have been regarded as the origin of SMSI because these two are hard to decouple in traditional supported metal catalysts. In this work, a TiOx/Au/Al2O3 quasi-model catalyst was fabricated by inversely depositing a minimal amount of TiOx on the surface of Au nanoparticles, where the charge transfer between TiOx and Au was minimized. As experimentally demonstrated, under high-temperature reduction-reoxidation treatment, the surface TiOx undergoes a wetting-dewetting process, accompanied by the reversible suppression and recovery of the adsorption capability, during which the electron transfer between TiOx and Au is negligible. This work suggests that charge transfer may not be the driving force for the occurrence of SMSI, contributing to a deeper understanding of the SMSI mechanism.

Cyclopentanone (CPO) is a versatile chemical intermediate with great industrial relevance. In this work, a sustainable one-pot process converting xylose to CPO was developed via biphasic solvent engineering and a multifunctional Co/Nb2O5 catalyst, overcoming challenges of intermediate condensation and catalyst poisoning. Biphasic solvent system was formulated to integrate the two-stage process, based on the partitioning behavior of key intermediates to avoid unfavorable condensation while maintaining effective acid-assisted ring arrangement in aqueous phase. Co/Nb2O5 outperformed noble metals with 53 % CPO selectivity, attributed to its dual Bronsted/Lewis acidity, moderate hydrogenation capability, and resistance to carboxylic acid byproducts poisoning. Further structure-activity relationship analysis demonstrated that reduction temperature dependent Co delta+ species are critical for FFR conversion, with Co delta+/Cototal ratio presented a linear correlation with FFR conversion rate. This integrated strategy eliminates energy-intensive steps, offering a practical guidance toward catalytic reaction system design for facile and efficient one-pot conversion of xylose to industrially high-value compounds.

Alloying Cu-based catalysts by doping other metals at single atom level is an effective way to improve their hydrogenation performance of biomass-derived molecules. However, the application of Cu-based single atom alloy catalyst in the catalytic hydrogen transfer reaction system remains to be unrevealed. Here, we develop Al2O3 supported CuPd alloy catalysts, among which the single atom alloy catalyst with Pd dispersed in single atomic level on the surface was successfully obtained by controlling the metal amount, such as Cu8Pd1/Al2O3 with the Cu/Pd Molar ratio of 8: 1. The catalytic performance for furfural hydrodeoxygenation to 2-methylfuran of the CuPd/Al2O3 catalysts, using isopropanol as a hydrogen donor, shows a volcano-type relationship to the Cu/Pd ratio. The highest 2-methylfuran yield (81% at 220 degrees C) was achieved on the single atom alloy catalyst Cu8Pd1/Al2O3. The underlying reaction mechanism of furfural hydrodeoxidation on Cu8Pd1/Al2O3 was revealed by a series of isotopic labeling experiments, that the furfural was firstly hydrogenated to be furfuralcohol by a metal site-mediated catalytic transfer hydrogenation pathway, and then the furfuralcohol was converted to be 2methylfuran by a Lewis acid-mediated furan ring activation route. The weak Lewis acid site that formed by single atom Pd alloyed with CuO matrix on Cu8Pd1/Al2O3 was proposed as the active site for the highly selective generation of 2-methylfuran.

Alkyl levulinates act as crucial additives in gasoline and biodiesel and are largely produced through esterification of levulinic acid (LA) with alcohols using homogeneous acids suffering from equipment corrosion and low reusability issues. Here, in this work, a homogeneous phosphotungstic acid (HPW) catalyst was heterogenized via incorporation on a 2D imine-based covalent organic framework material (LZU1) to obtain a heterogeneous HPW-LZU1 catalyst. The material synthesis process was comprehensively monitored through 1H NMR, solid 13C MAS NMR, ATR-FTIR, etc. When the HPW/LZU1 mass ratio was 8.6, the HPW-LZU1 catalyst exhibited an excellent catalytic activity, with >90% conversion of LA and 100% selectivity of alkyl levulinates obtained, comparable to the HPW catalyst. Catalytic performance without obvious decrease after five cycles demonstrated excellent stability and reusability of the as-prepared catalyst. In situ FTIR study shows that LA was dominantly adsorbed on the Bro''nsted acid sites, while methanol was adsorbed on the Bro''nsted and Lewis acid sites. The HPW-pi interaction-induced electron delocalization effect over the catalyst effectively enhanced the adsorption of LA and alcohols and the attack of alcohols to LA through AAc1 mechanism, attributing to the high catalytic performance of the catalyst.

Supported metal nanoclusters (NCs) are regarded as the next generation of catalyst that bridge the nanocatalyst and single-atom catalyst. However, feasible fabrication of thermally stable NCs has remained a daunting challenge. In this paper, the first part of an extended work, we report a simple route to fabricate Pt NCs in size of around 1 nm through redispersion of Pt nanoparticles (NPs) or commercial PtO2 by a calcination treatment. Combining control experiments and detailed DFT simulation, the whole redispersion process was described and evidenced to proceed via a gas-phase trapping way: Under promotion of oxygen atmosphere and high temperature, volatile oxidized Pt monomers were firstly generated and then trapped by surface defects, forming special sites that preferentially induce the growth of clusters on them. The growing clusters have both size- and temperature-dependent stability, resulting a most stable size distribution of around 1 nm when fabricated at 550 °C. This work provides a feasible top-down strategy to fabricate highly dispersed metal clusters.

In this work, following Part 1 that has found a redispersion process from Pt nanoparticles (NPs, about 3.4 nm) to nanoclusters (NCs, about 1 nm) on TiO2 and elucidated its mechanism, we carefully investigated the catalytic performance of the obtained Pt NC catalyst in CO oxidation as well as the corresponding reaction mechanism. The Pt NC catalyst excels than its parent catalyst in terms of both intrinsic and apparent activity. Detailed studies by combining kinetic measurements, isotopic labeling reaction experiments, and low-temperature operando FT-IR unambiguously demonstrated that the Pt NCs deposited on TiO2 can form unique interfacial sites that enable to active O2 at very low temperature, thus the CO adsorbed on TiO2 can diffuses to, and reacts with, the activated oxygen, rendering a high activity at low temperatures. This work is contributory in understanding the origin of the high activity of the supported metal cluster catalysts.

Single-atom catalysts have become one of the hot topics in the heterogeneous catalysis field. However, the acquisition of its catalytic performance should be more rigorous in the next development. Here we discuss how to evaluate the activity of single-atom catalysts by appropriately comparing with their nanoparticle counterparts; we hope this perspective will benefit catalyst design and development in the future.

We propose and numerically investigate an image encoding and recovery system based on the inhibited spiking dynamics of a 1550-nm vertical-cavity surface-emitting laser (VCSEL) neuron. The results demonstrate that VCSELs subject to orthogonal optical injection can mimic the behaviors of biological neurons under external perturbations (stimuli) with different intensities and durations. Furthermore, VCSEL neuron can possess the encoding capability of binary-to-spike with GHz rate. Based on the post-processing techniques of spiking dynamics, the image recovery with bit error rate (BER) of 6.6× 10 −3 is achieved.

In this paper, we propose an all optical JK flip-flop system consisting of three vertical-cavity surface-emitting lasers with embedded saturable absorber (VCSEL-SAs) is proposed and numerically simulated. Also, the effects of injection intensity, delay and noise on the JK flip-flop are numerically analyzed. The results show that, based on the spiking dynamics of excited VCSEL-SA, the proposed all-optical JK flip-flop model can perform all the fundamental functions of conventional JK flip-flop under suitable bias current, injection intensity and perturbation delay between two trigger signals. Moreover, the noise has a little effect on the performance of JK flip-flop, but the proposed system has good robustness to the noise. The results provide a feasibility for the application of VCSEL-SA devices in the future ultrafast neuromorphic computing systems.

With the rapid development of society, modern technologies such as artificial intelligence, the Internet, multimedia, 5G communication, and big data services have been widely used in national production and daily life. Moreover, the demand for computing power in the whole society is increasing at a rate of at least 20% every year, which brings unprecedented challenges to the computing power of present computing systems. At present, the traditional Von Neumann architecture based on the separation of storage and computing has encountered bottlenecks including storage, computing speed, power consumption, etc. In addition, Moore's Law has also encountered bottlenecks due to the limitations of CMOS technology, and the development of integrated circuits has entered into a post-Moore era. Consequently, the research and development of artificial neural networks have attracted much attention, and photonic neural networks based on silicon-based electronic devices or optical devices have become the focus issue. Photonic neural networks can overcome the limitations of the von Neumann architecture and have the advantages of low power consumption and high speed when dealing with complex artificial intelligence tasks, which can provide a new feasible solution for solving complex problems such as decision-making, deep learning and optimization, pattern recognition, and perceptual information processing. In recent years, photonic neural networks have become a research hotspot due to their obvious advantages over traditional electronic methods in terms of speed and energy efficiency. As a result, neuromorphic photonic devices have attracted extensive attention. Amongst of them, semiconductor lasers have become an ideal artificial neuron due to similar response behavior to biological neuron and ultrafast response speed. In particular, VCSELs possess these advantages of small size, low power consumption, low cost, and high coupling efficiency with optical fibers. Therefore, exploring the nonlinear dynamic behaviors of VCSEL and their applications in these fields related to neuromorphic computing is expected to promote innovative development in the field of artificial intelligence. Recently, the spiking dynamics of VCSEL photonic neurons under external stimuli has been reported theoretically and experimentally. It is worth noting that introducing an extra Saturable Absorber (SA) into VCSEL can constitute an integrated two-section excitable laser (VCSEL-SA). Compared with the traditional photonic neuron model, this integrated photonic neuron can be used as a LIF model. Moreover, the spatiotemporal information can be encoded in the output spike signals of VCSEL-SA and the characteristics of biological neurons can be better simulated. In addition, VCSEL-SA can excite a shorter sub-nanosecond light pulse and its excitation threshold can also be flexibly controlled within a certain range. Therefore, the research and application of VCSEL-SA in the related fields of photonic neural network has become increasingly important. At present, optoelectronic hybrid information processing technology is still an important development direction for the future information technology field. Optoelectronic logic gate, as a key functional element in an optoelectronic hybrid system, can be applied to functional modules such as payload coding, parity checking, generation of ultra-high-speed pseudo-random sequences, and optical computing. So far, logic operation based on optoelectronic method has been realized. However, the traditional scheme usually has some disadvantages such as complex structure, multi-step or requiring relatively high power. Combining the cost efficiency of reconfigurable logic devices for future large-scale integration and unique advantages of VCSEL-SA, the optoelectronic logic gate based on VCSEL-SA can open a new path for future optoelectronic hybrid processing platform. In this paper, we propose a reconfigurable optoelectronic logic gate (NOT, NAND, NOR, XOR) based on the VCSEL-SA under the combined action of current modulation and optical injection, then the spiking dynamics of VCSEL-SA under current modulation are numerically studied, and the logic operation performance of VCSEL-SA is realized by the combined action of current modulation and optical injection. The research results show that, for the optical injection VCSEL-SA under current modulation, the optoelectronic logic gate can be realized within a certain bias current range. By selecting an appropriate modulation current, reconfigurable logic operations (NAND, NOR) can be realized, and the time delay between the two modulation signals has little effect on its performance. By changing the input mode of the current modulation signal and removing the optical injection signal, the VCSEL-SA can realize the XOR logic operation. In addition, the reconfigurable logic operation based on VCSEL-SA has good robustness to noise. These research results can provide a certain theoretical basis for future neuromorphic photonic networks to solve complex tasks.

Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application. Pd-based catalysts with high intrinsic activity are commonly employed, but usually suffer from low selectivity. Pd single-atom catalysts (SACs) usually exhibit outstanding ethylene selectivity due to the weak π-bonding ethylene adsorption. However, the preparation of high-loading and stable Pd SACs is still confronted with a great challenge. In this work, we report a simple strategy to fabricate Pd SACs by means of reducing conventional supported Pd catalysts at suitable temperatures to selectively encapsulate the co-existed Pd nanoparticles (NPs)/clusters. This is based on our new finding that single atoms only manifest strong metal-support interaction (SMSI) at higher reduction temperature than that of NPs/clusters. The derived Pd SACs (Pd1/CeO2 and Pd1/α-Fe2O3) were applied to acetylene selective hydrogenation, exhibiting much improved ethylene selectivity and high stability. This work offers a promising way to develop stable Pd SACs easily.

Metal-support interaction predominately determines the electronic structure of metal atoms in single-atom catalysts (SACs), largely affecting their catalytic performance. However, directly tuning the metal-support interaction in oxide supported SACs remains challenging. Here, we report a new strategy to subtly regulate the strong covalent metal-support interaction (CMSI) of Pt/CoFe 2 O 4 SACs by a simple water soaking treatment. Detailed studies reveal that the CMSI is weakened by the bonding of H + , generated from water dissociation, onto the interface of Pt-O-Fe, resulting in reduced charge transfer from metal to support and leading to an increase of C-H bond activation in CH 4 combustion by more than 50 folds. This strategy is general and can be extended to other CMSI-existed metal-supported catalysts, providing a powerful tool to modulating the catalytic performance of SACs.

Based on a vertical-cavity surface-emitting laser with saturated absorber (VCSEL-SA) subject to optical injection, we proposed an ultrafast pattern recognition scheme of four-bit binary data and theoretically investigated the recognition performances. The results show that, patterns recognition of different four-bit binary data at Gb/s rate can be realized by adjusting the injection weight of each bit number and optimal weight values can be determined. Although noise has some influences on the patterns recognition speed and accuracy, this proposed system has a certain robustness to noise on the whole. These results provide a promising application prospect for VCSEL-SA based ultrafast photonic neuromorphic system in pattern recognition field.

The discoveries and development of the oxidative strong metal–support interaction (OMSI) phenomena in recent years not only promote new and deeper understanding of strong metal–support interaction (SMSI) but also open an alternative way to develop supported heterogeneous catalysts with better performance. In this review, the brief history as well as the definition of OMSI and its difference from classical SMSI are described. The identification of OMSI and the corresponding characterization methods are expounded. Furthermore, the application of OMSI in enhancing catalyst performance, and the influence of OMSI in inspiring discoveries of new types of SMSI are discussed. Finally, a brief summary is presented and some prospects are proposed.