Alloying and confinement effects on hierarchically nanoporous CuAu for efficient electrocatalytic semi-hydrogenation of terminal alkynes.

Electrocatalytic alkynes semi-hydrogenation to produce alkenes with high yield and Faradaic efficiency remains technically challenging because of kinetically favorable hydrogen evolution reaction and over-hydrogenation. Here, we propose a hierarchically nanoporous Cu50Au50 alloy to improve electrocatalytic performance toward semi-hydrogenation of alkynes. Using Operando X-ray absorption spectroscopy and density functional theory calculations, we find that Au modulate the electronic structure of Cu, which could intrinsically inhibit the combination of H* to form H2 and weaken alkene adsorption, thus promoting alkyne semi-hydrogenation and hampering alkene over-hydrogenation. Finite element method simulations and experimental results unveil that hierarchically nanoporous catalysts induce a local microenvironment with abundant K+ cations by enhancing the electric field within the nanopore, accelerating water electrolysis to form more H*, thereby promoting the conversion of alkynes. As a result, the nanoporous Cu50Au50 electrocatalyst achieves highly efficient electrocatalytic semi-hydrogenation of alkynes with 94% conversion, 100% selectivity, and a 92% Faradaic efficiency over wide potential window. This work provides a general guidance of the rational design for high-performance electrocatalytic transfer semi-hydrogenation catalysts.

Nanoporous copper titanium tin (np-Cu2TiSn) Heusler alloy prepared by dealloying-induced phase transformation for electrocatalytic nitrate reduction to ammonia.

Heusler alloys are a series of well-established intermetallic compounds with abundant structure and elemental substitutions, which are considered as potentially valuable catalysts for integrating multiple reactions owing to the features of ordered atomic arrangement and optimized electronic structure. Herein, a nanoporous copper titanium tin (np-Cu2TiSn) Heusler alloy is successfully prepared by the (electro)chemical dealloying transformation method, which exhibits high nitrate (NO3-) reduction performance with an NH3 Faradaic efficiency of 77.14 %, an NH3 yield rate of 11.90 mg h-1 mg-1cat, and a stability for 100 h under neutral condition. Significantly, we also convert NO3- to high-purity ammonium phosphomolybdate with NH4+ collection efficiency of 83.8 %, which suggests a practical approach to convert wastewater nitrate into value-added ammonia products. Experiments and theoretical calculations reveal that the electronic structure of Cu sites is modulated by the ligand effect of surrounding Ti and Sn atoms, which can simultaneously enhance the activation of NO3-, facilitate the desorption of NH3, and reduce the energy barriers, thereby boosting the electrochemical nitrate reduction reaction.

Asymmetric Local Electric Field Induced by Dual Heteroatoms on Copper Boosts Efficient CO2 Reduction Over Ultrawide Potential Window.

Electrocatalytic reduction of CO2 powered by renewable electricity provides an elegant route for converting CO2 into valuable chemicals and feedstocks, but normally suffers from a high overpotential and low selectivity. Herein, Ag and Sn heteroatoms were simultaneously introduced into nanoporous Cu (np-Ag/Sn-Cu) mainly in the form of an asymmetric local electric field for CO2 electroreduction to CO in an aqueous solution. The designed np-Ag/Sn-Cu catalyst realizes a recorded 90% energy efficiency and a 100% CO Faradaic efficiency over ultrawide potential window (ΔE = 1.4 V), outperforming state-of-the-art Au and Ag-based catalysts. Density functional theory calculations combined with in situ spectroscopy studies reveal that Ag and Sn heteroatoms incorporated into Cu matrix could generate strong and asymmetric local electric field, which promotes the activation of CO2 molecules, enhances the stabilization of the *COOH intermediate, and suppresses the hydrogen evolution reaction, thus favoring the production of CO during CO2RR.

Epitaxial Growth of Two-Dimensional Nonlayered AuCrS2 Materials via Au-Assisted Chemical Vapor Deposition.

Two-dimensional (2D) nonlayered transition metal dichalcogenide (TMD) materials are emergent platforms for various applications from catalysis to quantum devices. However, their limited availability and nonstraightforward synthesis methods hinder our understanding of these materials. Here, we present a novel technique for synthesizing 2D nonlayered AuCrS2 via Au-assisted chemical vapor deposition (CVD). Our detailed structural analysis reveals the layer-by-layer growth of [AuCrS2] units atop an initial CrS2 monolayer, with Au binding to the adjacent monolayer of CrS2, which is in stark contrast with the well-known metal intercalation mechanism in the synthesis of many other 2D nonlayered materials. Theoretical calculations further back the crucial role of Cr in increasing the mobility of Au species and strengthening the adsorption energy of Au on CrS2, thereby aiding the growth throughout the CVD process. Additionally, the resulting free-standing nanoporous AuCrS2 (NP-AuCrS2) exhibits exceptional electrocatalytic properties for the hydrogen evolution reaction.

Platinum-Ruthenium Dual-Atomic Sites Dispersed in Nanoporous Ni0.85Se Enabling Ampere-Level Current Density Hydrogen Production.

Alkaline anion-exchange-membrane water electrolyzers (AEMWEs) using earth-abundant catalysts is a promising approach for the generation of green H2. However, the AEMWEs with alkaline electrolytes suffer from poor performance at high current density compared to proton exchange membrane electrolyzers. Here, atomically dispersed Pt-Ru dual sites co-embedded in nanoporous nickel selenides (np/Pt1Ru1-Ni0.85Se) are developed by a rapid melt-quenching approach to achieve highly-efficient alkaline hydrogen evolution reaction. The np/Pt1Ru1-Ni0.85Se catalyst shows ampere-level current density with a low overpotential (46 mV at 10 mA cm-2 and 225 mV at 1000 mA cm-2), low Tafel slope (32.4 mV dec-1), and excellent long-term durability, significantly outperforming the benchmark Pt/C catalyst and other advanced large-current catalysts. The remarkable HER performance of nanoporous Pt1Ru1-Ni0.85Se is attributed to the strong intracrystal electronic metal-support interaction (IEMSI) between Pt-Se-Ru sites and Ni0.85Se support which can greatly enlarge the charge redistribution density, reduce the energy barrier of water dissociation, and optimize the potential determining step. Furthermore, the assembled alkaline AEMWE with an ultralow Pt and Ru loading realizes an industrial-level current density of 1 A cm-2 at 1.84 volts with high durability.

Ni Single-Atom Bual Catalytic Electrodes for Long Life and High Energy Efficiency Zinc-Iodine Batteries.

Zinc-iodine batteries (Zn-I2) are extremely attractive as the safe and cost-effective scalable energy storage system in the stationary applications. However, the inefficient redox kinetics and "shuttling effect" of iodine species result in unsatisfactory energy efficiency and short cycle life, hindering their commercialization. In this work, Ni single atoms highly dispersed on carbon fibers is designed and synthesized as iodine anchoring sites and dual catalysts for Zn-I2 batteries, and successfully inhibit the iodine species shuttling and boost dual reaction kinetics. Theoretical calculations indicate that the reinforced d-p orbital hybridization and charge interaction between Ni single-atoms and iodine species effectively enhance the confinement of iodine species. Ni single-atoms also accelerate the iodine conversion reactions with tailored bonding structure of I─I bonds and reduced energy barrier for the dual conversion of iodine species. Consequently, the high-rate performance (180 mAh g-1 at 3 A g-1), cycling stability (capacity retention of 74% after 5900 cycles) and high energy efficiency (90% at 3 A g-1) are achieved. The work provides an effective strategy for the development of iodine hosts with high catalytic activity for Zn-I2 batteries.

Accelerating electrosynthesis of ammonia from nitrates using coupled NiO/Cu nanocomposites.

Herein, we report a nanocomposite electrocatalyst with coupled Cu and NiO, showing a high Faraday efficiency of 97% and excellent ammonia production rate (450 mg h-1 cm-2) for nitrate reduction. In situ UV-vis spectroscopic studies confirmed that the synergy between NiO and Cu could avoid NO2- enrichment and promote tandem nitrate reduction to ammonia synthesis.

Constructing Nanoporous Ir/Ta2 O5 Interfaces on Metallic Glass for Durable Acidic Water Oxidation.

Although proton exchange membrane water electrolyzers (PEMWE) are considered as a promising technique for green hydrogen production, it remains crucial to develop intrinsically effective oxygen evolution reaction (OER) electrocatalysts with high activity and durability. Here, a flexible self-supporting electrode with nanoporous Ir/Ta2O5 electroactive surface is reported for acidic OER via dealloying IrTaCoB metallic glass ribbons. The catalyst exhibits excellent electrocatalytic OER performance with an overpotential of 218 mV for a current density of 10 mA cm-2 and a small Tafel slope of 46.1 mV dec-1 in acidic media, superior to most electrocatalysts. More impressively, the assembled PEMWE with nanoporous Ir/Ta2 O5 as an anode shows exceptional performance of electrocatalytic hydrogen production and can operate steadily for 260 h at 100 mA cm-2 . In situ spectroscopy characterizations and density functional theory calculations reveal that the modest adsorption of OOH* intermediates to active Ir sites lower the OER energy barrier, while the electron donation behavior of Ta2 O5 to stabilize the high-valence states of Ir during the OER process extended catalyst's durability.

Sulfur-Stabilizing Ultrafine High-Entropy Alloy Nanoparticles on MXene for Highly Efficient Ethanol Electrooxidation.

High-entropy alloys (HEAs) are significantly promising candidates for heterogeneous catalysis, yet the controllable synthesis of ultrafine HEA nanoparticles (NPs) remains a formidable challenge due to severe thermal sintering during the high-temperature fabrication process. Herein, we report a sulfur-stabilizing strategy to construct ultrafine HEA NPs with an average diameter of 4.02 nm supported on sulfur-modified Ti3C2Tx (S-Ti3C2Tx) MXene, on which the strong interfacial metal-sulfur interactions between HEA NPs and the S-Ti3C2Tx supports significantly increase the interfacial adhesion strength, thus greatly suppressing nanoparticle sintering by retarding both particle migration and metal atom diffusion. The representative quinary PtPdCuNiCo HEA-S-Ti3C2Tx exhibits excellent catalytic performance toward alkaline ethanol oxidation reaction (EOR) with an ultrahigh mass activity of 7.03 A mgPt+Pd-1, which is 4.34 and 5.17 times higher than those of the commercial Pt/C and Pd/C catalysts, respectively. In situ attenuated total reflection-infrared spectroscopy studies reveal that the high intrinsic catalytic activity for the EOR can be ascribed to the synergy of different catalytically active sites of HEA NPs and the well-designed interfacial metal-sulfur interactions.

Efficient electrosynthesis of formamide from carbon monoxide and nitrite on a Ru-dispersed Cu nanocluster catalyst.

Conversion into high-value-added organic nitrogen compounds through electrochemical C-N coupling reactions under ambient conditions is regarded as a sustainable development strategy to achieve carbon neutrality and high-value utilization of harmful substances. Herein, we report an electrochemical process for selective synthesis of high-valued formamide from carbon monoxide and nitrite with a Ru1Cu single-atom alloy under ambient conditions, which achieves a high formamide selectivity with Faradaic efficiency of 45.65 ± 0.76% at -0.5 V vs. RHE. In situ X-ray absorption spectroscopy, coupled with in situ Raman spectroscopy and density functional theory calculations results reveal that the adjacent Ru-Cu dual active sites can spontaneously couple *CO and *NH2 intermediates to realize a critical C-N coupling reaction, enabling high-performance electrosynthesis of formamide. This work offers insight into the high-value formamide electrocatalysis through coupling CO and NO2- under ambient conditions, paving the way for the synthesis of more-sustainable and high-value chemical products.

Palladium metallene confined on MXene with increased hydroxyl binding strength for highly efficient ethanol electrooxidation.

Rational design and synthesis of high-performance electrocatalysts for ethanol oxidation reaction (EOR) is crucial to large-scale commercialization of direct ethanol fuel cells, but it is still an incredible challenge. Herein, a unique Pd metallene/Ti3C2Tx MXene (Pdene/Ti3C2Tx)-supported electrocatalyst is constructed via an in-situ growth approach for high-efficiency EOR. The resulting Pdene/Ti3C2Tx catalyst achieves an ultrahigh mass activity of 7.47 A mgPd-1 under alkaline condition, as well as high tolerance to CO poisoning. In situ attenuated total reflection-infrared spectroscopy studies combined with density functional theory calculations reveal that the excellent EOR activity of Pdene/Ti3C2Tx catalyst is attributed to the unique and stable interfaces which reduce the reaction energy barrier of *CH3CO intermediate oxidation and facilitate oxidative removal of CO poisonous species by increasing the Pd-OH binding strength.

Pd Atomic Engineering of Nanoporous Ni/NiO for Efficient Nitrophenol Hydrogenation Reaction.

The catalytic hydrogenation of nitrophenols is widely utilized for both industrial synthesis and environmental protection, thus efficient and cost-effective catalysts are in urgent need. Still, the cost and scarcity of the materials still inhibit their application and the active sites are not well specified, especially in the complex catalysts. Herein, we developed an atomic Pd-doped nanoporous Ni/NiO (Pd1@np-Ni/NiO) catalyst via facial dealloying for efficient nitrophenol hydrogenation reaction under mild conditions. Pd1@np-Ni/NiO achieves an excellent specific activity (1301 min-1 mgPd-1, 35.2 times that of commercial Pd/C), nearly 100% selectivity, and continuous reproducibility. The catalytic performance is highly relevant to the Ni sites on the catalysts regarding the exposure sites and the intrinsic property. The metal/metal oxide interfacial structure could cooperatively accelerate the catalytic reaction kinetics. The atomic dopants could effectively modulate the electronic structure, facilitate the absorption of molecules, and reduce the energy barrier of catalytic hydrogenation reaction. Based on the efficient catalyst, the protype nitrophenol//NaBH4 battery is designed for efficient material conversion and power output, which is very attractive for green energy systems.

Growth of nanostructured Cu3Al alloy films by magnetron sputtering for non-enzymatic glucose-sensing applications.

Enzymatic glucose sensors usually exhibit excellent sensitivity and selectivity but suffer from poor stability due to the negative influence of temperature and humidity on enzyme molecules. As compared to enzymatic glucose sensors, non-enzymatic counterparts are generally more stable but are facing challenges in concurrently improving both sensitivity and selectivity of a trace amount of glucose molecules in physiological samples such as saliva and sweat. Here, a novel non-enzymatic glucose sensor based on nanostructured Cu3Al alloy films has been fabricated by a facile magnetron-sputtering followed by controllable electrochemical etching approach. Since the metal Al is more reductive than Cu, by selectively etching aluminum in the Cu3Al alloys, nanostructured alloy films were obtained with increased surface contact area and electrocatalytic active sites which resulted in enhanced glucose-sensing performance. Thus, non-enzymatic glucose sensors based on nanostructured Cu3Al alloy films not only exhibited a high sensitivity of 1680 µA mM-1 cm-2 but also achieved a reliable selectivity to glucose without interference by other species in physiological samples. Consequently, this study sparked the potential for the development of non-enzymatic biosensors for the continuous monitoring of blood glucose levels with high sensitivity and impressive selectivity for glucose molecules.

Engineering CoP Alloy Foil to a Well-Designed Integrated Electrode Toward High-Performance Electrochemical Energy Storage.

Nanostructured integrated electrodes with binder-free design show great potential to solve the ever-growing problems faced by currently commercial lithium-ion batteries such as insufficient power and energy densities. However, there are still many challenging problems limiting practical application of this emerging technology, in particular complex manufacturing process, high fabrication cost, and low loading mass of active material. Different from existing fabrication strategies, here using a CoP alloy foil as a precursor  a simple neutral salt solution-mediated electrochemical dealloying method to well address the above issues is demonstrated. The resultant freestanding mesoporous np-Co(OH)x /Co2 P product possesses not only active compositions of high specific capacity and large electrode packing density (>3.0 g cm-3 ) to meet practical capacity requirements, high-conductivity and well-developed nanoporous framework to achieve simultaneously fast ion and electron transfer, but also interconnected ligaments and suitable free space to ensure strong structural stability. Its comprehensively excellent electrochemical energy storage (EES) performances in both lithium/sodium-ion batteries and lithium-ion capacitors can further illustrate the effectiveness of the integrated electrode preparation strategy, such as remarkable reversible specific capacities/capacitances, dominated pseudo-capacitive EES mechanism, and ultra-long cycling life. This study provides new insights into preparation and design of high-performance integrated electrodes for practical applications.

Rapid Melt-Quenching Enables General Synthesis of High-Loading Single-Atom Catalysts with Bicontinuous Nanoporous Structure.

Single-atom catalysts have attracted extensive attention due to their unique atomic structures and extraordinary activities in catalyzing chemical reactions. However, the lack of general and efficient approaches for producing high-density single atoms on suitably tailored supporting matrixes hinders their industrial applications. Here, a rapid melt-quenching strategy with high throughput to synthesize single atoms with high metal-atom loadings of up to 9.7 wt% or 2.6 at% on nanoporous metal compounds is reported, representing several-fold improvements compared to benchmarks in the literature. Mechanism characterizations reveal that the high-temperature melting provides the essential liquid environment and activation energy to achieve the atomization of metals, while the following rapid-quenching pins the isolated metal atoms and stabilizes the coordination environment. In comparison with carbon-supported single-atom catalysts, various collaboration combinations of single atoms and nanoporous metal compounds can be synthesized using the strategy, thus achieving efficient hydrazine oxidation-assisted H2 production. This synthesis protocol is highly compatible with automatic operation, which provides a feasible and general route to design and manufacture specific single-atom catalysts with tunable atomic metal components and supporting matrixes, thus promoting the deployment of single-atom catalysts for various energy technology applications.

Scalable-doped Nanoporous 1T″ ReSe2 via a General Surface Co-Alloy Strategy.

Reliable and controllable doping of 2D transition metal dichalcogenides is an efficient approach to tailor their physicochemical properties and expand their functional applications. However, precise control over dopant distribution and scalability of the process remains a challenge. Here, we report a general method to achieve scalable in situ doping of centimeter-sized bicontinuous nanoporous ReSe2 films with transition metal atoms via surface coalloy growth. The distinct strains induced by the bending curvature of nanoporous structures and uniform dopants result in a local 1T' to 1T″ structure phase transition over nanoporous ReSe2 films. The as-prepared nanoporous Ru-ReSe2 with high 1T″ phase exhibits preferable electrochemical activity in hydrogen evolution reaction. The work demonstrates a unique and general approach to synthesize uniformly-doped transition metal dichalcogenides with 3D bicontinuous nanoporous structure, which can be scaled up to batch production for various applications.

Aligned InS Nanorods for Efficient Electrocatalytic Carbon Dioxide Reduction.

Electrochemical CO2 reduction technology can combine renewable energy sources with carbon capture and storage to convert CO2 into industrial chemicals. However, the catalytic activity under high current density and long-term electrocatalysis process may deteriorate due to agglomeration, catalytic polymerization, element dissolution, and phase change of active substances. Here, we report a scalable and facile method to fabricate aligned InS nanorods by chemical dealloying. The resulting aligned InS nanorods exhibit a remarkable CO2RR activity for selective formate production at a wide potential window, achieving over 90% faradic efficiencies from -0.5 to -1.0 V vs reversible hydrogen electrode (RHE) under gas diffusion cell, as well as continuously long-term operation without deterioration. In situ electrochemical Raman spectroscopy measurements reveal that the *OCHO* species (Bidentate adsorption) are the intermediates that occurred in the reaction of CO2 reduction to formate. Meanwhile, the presence of sulfur can accelerate the activation of H2O to react with CO2, promoting the formation of *OCHO* intermediates on the catalyst surface. Significantly, through additional coupling anodic methanol oxidation reaction (MOR), the unusual two-electrode electrolytic system allows highly energy-efficient and value-added formate manufacturing, thereby reducing energy consumption.

Atomic Engineering Catalyzed Redox Kinetics of Nix Co1-x (OH)2 on Nanoporous Phosphide Electrode for Efficient Ni-Zn Batteries.

Aqueous nickel-zinc (Ni-Zn) batteries with excellent safety and environmental benignity are promising candidates for sustainable energy storage. However, the inferior conductivity and inevitable phase transition of trditional Ni-based cathodes limit the redox kinetics and lead to restricted electrode specific capacity and device energy density. Here, a Nix Co1-x (OH)2 electrode doped with Pd, Ag, and Au atoms is constructed for catalyzing the redox kinetics on the conductive nanoporous phosphide. Density functional theory calculations and experimental results reveal that the introduction of the Ag atomic dopants can effectively modulate the electron structure and optimize the OH- adsorption energy, thereby accelerating the catalyzed redox kinetics of Nix Co1-x (OH)2 by the facilitated charge transfer at the active sites around metal dopants. Consequently, the assembled Ni-Zn battery delivers an ultrahigh power density of 7.85 W cm-3 and energy density of 49.53 mW h cm-3 , with a long-term cycling stability. The cooperation of atomic catalysis and redox kinetics will inspire more exploration of efficient energy materials and devices.

Nanoporous Intermetallic SnTe Enables Efficient Electrochemical CO2 Reduction into Formate via Promoting the Fracture of Metal-Oxygen Bonding.

Electrochemical reduction of CO2 into formate product is considered the most practical significance link in the carbon cycle. Developing cheap and efficient electrocatalysts with high selectivity for formate on a wide operated potential window is desirable yet challenging. Herein, nanoporous ordered intermetallic tin-tellurium (SnTe) is synthesized with a greater reduction performance for electrochemical CO2 to formate reduction compared to bare Sn. This nanoporous SnTe achieves 93% Faradaic efficiency for formate production and maintains over 90% Faradaic efficiency at a wide voltage range from -1.0 to -1.3 V versus reversible hydrogen electrode (RHE), together with 60 h stability. Combining operando Raman spectroscopy studies with density functional theory calculations reveals that strong orbital interaction between Sn and neighboring tellurium (Te) in the intermetallic SnTe can lower the barriers of the oxygen cutoff hydrogenation and desorption steps by promoting the fracture of bond between metal and oxygen, leading to the significant enhancement of formate production.

A General Strategy for Engineering Single-Metal Sites on 3D Porous N, P Co-Doped Ti3C2TX MXene.

Two-dimensional (2D) MXenes have been developed to stabilize single atoms via various methods, such as vacancy reduction and heteroatom-mediated interactions. However, anchoring single atoms on 3D porous MXenes to further increase catalytic active sites and thus construct electrocatalysts with high activity and stability remains unexplored. Here, we reported a general synthetic strategy for engineering single-metal sites on 3D porous N, P codoped Ti3C2TX nanosheets. Through a "gelation-and-pyrolysis" process, a series of atomically dispersed metal catalysts (Pt, Ir, Ru, Pd, and Au) supported by N, P codoped Ti3C2TX nanosheets with 3D porous structure can be obtained and serve as efficient catalysts for the electrochemical hydrogen evolution reaction (HER). As a result of the favorable electronic and geometric structure of N(O), P-coordinated metal atoms optimizing catalytic intermediates adsorption and 3D porous structure exposing the active surface sites and facilitating charge/mass transfer, the as-synthesized Pt SA-PNPM catalyst shows ∼20-fold higher activity than the commercial Pt/C catalyst for electrochemical HER over a wide pH range.