Recent Progress in Metal Phosphorous Chalcogenides: Potential High-Performance Electrocatalysts

Laser-induced hole coherence in 2D antiferromagnet MPS3 through spatial self-phase modulation

Transition metal phosphorus sulfides (MPS3), a family of two-dimensional magnetic materials with a van der Waals structure, exhibit promising applications in nonlinear optical devices. The emergence of carrier coherence in MPS3 is a fascinating topic in coherently controlling the nonlinear effect (or other novel phenomena). Herein, we systematically investigated the third-order nonlinear optical responses of MPS3 (M = Ni, Fe, Mn) flake suspensions based on spatial self-phase modulation (SSPM) effect. The effective monolayer third-order nonlinear susceptibilities (χmonolayer(3)) of NiPS3 and MnPS3 are obtained for the first time at multiple wavelengths. Our results show that NiPS3 has a higher χmonolayer(3) value (3.59 × 10-9 e.s.u. or 5.01 × 10-17 m2V-2 at 405 nm excitation) than those of FePS3 and MnPS3. Furthermore, we laser-induced non-local hole coherence in MPS3 based on SSPM, where the origin of excited-state holes is analyzed from electronic structures. The relationships between hole mobility μ hole, effective mass m h∗, and χmonolayer(3) for the three materials fulfill the previous investigation results. Because laser-induced hole coherence has rarely been reported, our investigation enriches the coherent regulation of two-dimensional magnetic MPS3 materials, enabling potential applications in all-optical devices.

Efficient Charge Separation in Ag/PCN/UPDI Ternary Heterojunction for Optimized Photothermal-Photocatalytic Performance via Tandem Electric Fields

Charge separation driven by the internal electric field is a research hotspot in photocatalysis. However, it remains challenging to accurately control the electric field to continuously accelerate the charge transfer. Herein, a strategy of constructing a tandem electric field to continuously accelerate charge transfer in photocatalysts is proposed. The plasma electric field, interface electric field, and intramolecular electric field are integrated into the Ag/g-C3N4/urea perylene imide (Ag/PCN/UPDI) ternary heterojunction to achieve faster charge separation and longer carrier lifetime. The triple electric fields function as three accelerators on the charge transport path, promoting the separation of electron-hole pairs, accelerating charge transfer, enhancing light absorption, and increasing the concentration of energetic electrons on the catalyst. The H2 evolution rate of Ag/PCN/UPDI is 16.8 times higher than that of pristine PDI, while the degradation rate of oxytetracycline is increased by 4.5 times. This new strategy will provide a groundbreaking idea for the development of high-efficiency photocatalysts.

Catalysts for C-N coupling in urea electrosynthesis under ambient conditions from carbon dioxide and nitrogenous species

Urea is an indispensable nitrogen-containing organic compound in modern human life. However, the current industrial synthesis of urea involves ammonia, which is produced through the Haber-Bosch process under harsh reaction conditions, causing huge energy consumption and heavy environmental pollution. Electrochemical reduction of carbon dioxide (CO2) and nitrogenous species (N2, NOx- and NO) have achieved significant progress, offering a promising approach for the electrochemical C-N coupling to produce urea under ambient conditions. Urea synthesis driven by renewable electricity represents a suitable alternative to the traditional process, contributing to the goal of carbon neutrality and nitrogen cycles. However, challenges such as low yield rate, poor selectivity and unveiled reaction mechanisms still need to be addressed. This review provides a summary of the latest catalysts utilized in urea electrosynthesis, aiming to provide guidance and prospects for the development of high-performance catalysts.

Computational screening of layered metal chalcogenide materials for HER electrocatalysts, and its synergy with experiments

Layered materials have emerged as attractive candidates in our search for abundant, inexpensive and efficient hydrogen evolution reaction (HER) catalysts, due to larger specific area these offer. Among these, transition metal dichalcogenides have been studied extensively, while ternary transition metal tri-chalcogenides have emerged as promising candidates recently. Computational screening has emerged as a powerful tool to identify the promising materials out of an initial set for specific applications, and has been employed for identifying HER catalysts also. This article presents a comprehensive review of how computational screening studies based on density functional calculations have successfully identified the promising materials among the layered transition metal di- and tri-chalcogenides. Synergy of these computational studies with experiments is also reviewed. It is argued that experimental verification of the materials, predicted to be efficient catalysts but not yet tested, will enlarge the list of materials that hold promise to replace expensive platinum, and will help ushering in the much awaited hydrogen economy.

Reliable Memristor Crossbar Array Based on 2D Layered Nickel Phosphorus Trisulfide for Energy-Efficient Neuromorphic Hardware

Designing reliable and energy-efficient memristors for artificial synaptic arrays in neuromorphic computing beyond von Neumann architecture remains a challenge. Here, memristors based on emerging layered nickel phosphorus trisulfide (NiPS3 ) are reported that exhibit several favorable characteristics, including uniform bipolar nonvolatile switching with small operating voltage (<1 V), fast switching speed (< 20 ns), high On/Off ratio (>102 ), and the ability to achieve programmable multilevel resistance states. Through direct experimental evidence using transmission electron microscopy and energy dispersive X-ray spectroscopy, it is revealed that the resistive switching mechanism in the Ti/NiPS3 /Au device is related to the formation and dissolution of Ti conductive filaments. Intriguingly, further investigation into the microstructural and chemical properties of NiPS3 suggests that the penetration of Ti ions is accompanied by the drift of phosphorus-sulfur ions, leading to induced P/S vacancies that facilitate the formation of conductive filaments. Furthermore, it is demonstrated that the memristor, when operating in quasi-reset mode, effectively emulates long-term synaptic weight plasticity. By utilizing a crossbar array, multipattern memorization and multiply-and-accumulate (MAC) operations are successfully implemented. Moreover, owing to the highly linear and symmetric multiple conductance states, a high pattern recognition accuracy of ≈96.4% is demonstrated in artificial neural network simulation for neuromorphic systems.

Current Progress of Mo-Based Metal Organic Frameworks Derived Electrocatalysts for Hydrogen Evolution Reaction

As an important half-reaction for electrochemical water splitting, electrocatalytic hydrogen evolution reaction suffers from sluggish kinetics, and it is still urgent to search high efficiency non-platinum-based electrocatalysts. Mo-based catalysts such as Mo2 C, MoO2 , MoP, MoS2 , and MoNx have emerged as promising alternatives to Pt/C owing to their similar electronic structure with Pt and abundant reserve of Mo. On the other hand, due to the adjustable topology, porosity, and nanostructure of metal organic frameworks (MOFs), MOFs are extensively used as precursors to prepare nano-electrocatalysts. In this review, for the first time, the progress of Mo-MOFs-derived electrocatalysts for hydrogen evolution reaction is summarized. The preparation method, structures, and catalytic performance of the catalysts are illustrated based on the types of the derived electrocatalysts including Mo2 C, MoO2 , MoP, MoS2 , and MoNx . Especially, the commonly used strategies to improve catalytic performance such as heteroatoms doping, constructing heterogeneous structure, and composited with noble metal are discussed. Moreover, the opportunities and challenges in this area are proposed to guide the designment and development of Mo-based MOF derived electrocatalysts.

Atomically dispersed Pd on defective BN nanosheets for nitrite electroreduction to ammonia

Electrocatalytic NO2- reduction to NH3 (NO2RR) offers a prospective strategy to concurrently achieve polluted NO2- removal and effective NH3 electrosynthesis. In this work, we report atomically dispersed Pd on defective BN nanosheets (Pd1/BN) as an efficient catalyst for the NO2RR, achieving the highest NH3-Faradaic efficiency of 91.7% with an NH3 yield rate of 347.1 μmol h-1 cm-2 at -0.6 V vs. RHE, superior to those of most previously reported electrocatalysts. Theoretical computations reveal the isolated Pd sites as catalytic centers to selectively adsorb NO2- and accelerate NO2--to-NH3 hydrogenation process with a minimized reaction barrier, eventually contributing to the considerably enhanced NO2RR selectivity and activity of Pd1/BN.

Defect Enriched Tungsten Oxide Phosphate with Strategic Sulfur Doping for Effective Seawater Oxidation

The intrinsic ability of defects within the electrocatalysts can be judiciously utilized in designing robust electrocatalysts for efficient seawater oxidation. Herein, we have fabricated a novel tungsten oxide phosphate (W12PO38.5) with optimized sulfur doping triggering the insertion of a large number of defect sites. This allows for boosted OER performance in alkaline freshwater as well as seawater, avoiding the unwanted chlorine evolution reaction. The optimized electrocatalyst achieved high current densities of 500 mA cm-2 at an overpotential of just 387 mV in fresh water and 100 mA cm-2 at 380 mV in alkaline seawater for OER. Besides the excellent catalytic performances, the developed electrocatalyst appeared to be a durable catalyst as well. An interesting electrocatalytic activation caused by the generous electronic redistribution led the electrocatalyst to achieve great stability over 100 h at a 100 mA cm-2 current density in alkaline real seawater.

Structural Design Induced Electronic Optimization in Single-Phase MoCoP Nanocrystal for Boosting Oxygen Reduction, Oxygen Evolution, and Hydrogen Evolution

Structural and compositional design of multifunctional materials is critical for electrocatalysis, but their rational modulation and effective synthesis remain a challenge. Herein, a controllable one-pot synthesis for construction of trifunctional sites and preparation of porous structures is adopted for synthesizing dispersed MoCoP sites on N, P codoped carbonized substance. This tunable synthetic strategy also endorses the exploration of the electrochemical activities of Mo (Co)-based unitary, Mo/Co-based dual and MoCo-based binary metallic sites. Eventually benefiting from the structural regulation, MoCoP-NPC shows excellent oxygen reduction abilities with a half-wave potential of 0.880 V, and outstanding oxygen evolution and hydrogen evolution performance with an overpotential of 316 mV and 91 mV, respectively. MoCoP-NPC-based Zn-air battery achieves excellent cycle stability for 300 h and a high open-circuit voltage of 1.50 V. When assembled in a water-splitting device, MoCoP-NPC reaches 10 mA cm-2 at 1.65 V. Theoretical calculations demonstrate that the Co atom in the single-phase MoCoP has a low energy barrier for oxygen evolution reaction (OER) owing to the migration of Co 3d orbital toward the Fermi level. This work shows a simplified method for controllable preparation of prominent trifunctional catalysts.

Metal Phosphorous Chalcogenide: A Promising Material for Advanced Energy Storage Systems

The development of efficient and affordable electrode materials is crucial for clean energy storage systems, which are considered a promising strategy for addressing energy crises and environmental issues. Metal phosphorous chalcogenides (MPX3 ) are a fascinating class of two-dimensional materials with a tunable layered structure and high ion conductivity, making them particularly attractive for energy storage applications. This review article aims to comprehensively summarize the latest research progress on MPX3 materials, with a focus on their preparation methods and modulation strategies. Additionally, the diverse applications of these novel materials in alkali metal ion batteries, metal-air batteries, and all-solid-state batteries are highlighted. Finally, the challenges and opportunities of MPX3 materials are presented to inspire their better potential in energy storage applications. This review provides valuable insights into the promising future of MPX3 materials in clean energy storage systems.

Water-Stable Fluorous Metal-Organic Frameworks with Open Metal Sites and Amine Groups for Efficient Urea Electrocatalytic Oxidation

Urea oxidation reaction (UOR) is one of the promising alternative anodic reactions to water oxidation that has attracted extensive attention in green hydrogen production. The application of specifically designed electrocatalysts capable of declining energy consumption and environmental consequences is one of the major challenges in this field. Therefore, the goal is to achieve a resistant, low-cost, and environmentally friendly electrocatalyst. Herein, a water-stable fluorinated Cu(II) metalorganic framework (MOF) {[Cu2 (L)(H2 O)2 ]·(5DMF)(4H2 O)}n (Cu-FMOF-NH2 ; H4 L = 3,5-bis(2,4-dicarboxylic acid)-4-(trifluoromethyl)aniline) is developed utilizing an angular tetracarboxylic acid ligand that incorporates both trifluoromethyl (-CF3 ) and amine (-NH2 ) groups. The tailored structure of Cu-FMOF-NH2 where linkers are connected by fluoride bridges and surrounded by dicopper nodes reveals a 4,24T1 topology. When employed as electrocatalyst, Cu-FMOF-NH2 requires only 1.31 V versus reversible hydrogen electrode (RHE) to deliver 10 mA cm-2 current density in 1.0 m KOH with 0.33 m urea electrolyte and delivered an even higher current density (50 mA cm-2 ) at 1.47 V versus RHE. This performance is superior to several reported catalysts including commercial RuO2 catalyst with overpotential of 1.52 V versus RHE. This investigation opens new opportunities to develop and utilize pristine MOFs as a potential electrocatalyst for various catalytic reactions.

Porous and Partially Dehydrogenated Fe2+ -Containing Iron Oxyhydroxide Nanosheets for Efficient Electrochemical Nitrogen Reduction Reaction (ENRR)

The design and development of efficient catalysts for electrochemical nitrogen reduction reaction (ENRR) under ambient conditions are critical for the alternative ammonia (NH3 ) synthesis from N2 and H2 O, wherein iron-based electrocatalysts exhibit outstanding NH3 formation rate and Faradaic efficiency (FE). Here, the synthesis of porous and positively charged iron oxyhydroxide nanosheets by using layered ferrous hydroxide as a starting precursor, which undergoes topochemical oxidation, partial dehydrogenated reaction, and final delamination, is reported. As the electrocatalyst of ENRR, the obtained nanosheets with a monolayer thickness and 10-nm mesopores display exceptional NH3 yield rate (28.5 µg h-1 mgcat. -1 ) and FE (13.2%) at a potential of -0.4 V versus RHE in a phosphate buffered saline (PBS) electrolyte. The values are much higher than those of the undelaminated bulk iron oxyhydroxide. The larger specific surface area and positive charge of the nanosheets are beneficial for providing more exposed reactive sites as well as retarding hydrogen evolution reaction. This study highlights the rational control on the electronic structure and morphology of porous iron oxyhydroxide nanosheets, expanding the scope of developing non-precious iron-based highly efficient ENRR electrocatalysts.

Amorphous Fe-Co oxide as an active and durable bifunctional catalyst for the urea-assisted H2 evolution reaction in seawater

In this study, we prepared amorphous iron-cobalt oxide through the dealloying of trimetallic FeCoAl, showing excellent performance in both urea oxidation and hydrogen evolution reactions (UOR and HER) in alkaline seawater. The catalyst demonstrated stable UOR and HER activity during long-term operations due to the abundant active sites and oxygen vacancies. The catalyst required applied potentials of 1.52 and -0.185 V to yield 100 mA cm-2 for the UOR and HER, respectively. Moreover, when used as both the cathode and anode, the electrolyzer required a working voltage of 1.68 V to yield 100 mA cm-2 for urea-assisted hydrogen production.

High entropy alloy nanoparticles as efficient catalysts for alkaline overall seawater splitting and Zn-air batteries

High entropy alloys (HEAs) are those metallic materials that consist of five or more elements. Compared with conventional alloys, they have much more catalytic active sites due to unique structural characteristics such as high entropy effect and lattice distortion, endowing them with promising applications in the region of hydrolysis catalysts. Herein, we successfully loaded high-entropy alloys onto carbon nanotubes (FeNiCoMnRu@CNT) by hydrothermal means. It exhibits excellent HER and OER properties in alkaline seawater. To accomplish two-electrode total water splitting when constructed into Zn air cells, it only needed 1.6 V, and the timing voltage curve showed a steady current density of 10 mA cm^-2 during constant electrolysis for more than 30 h in alkaline seawater. The remarkably high HER and OER activity of FeNiCoMnRu@CNT HEAs NPS indicates the potentially broad application prospect of HEAs for Zn air battery.

Cathode materials for halide-based aqueous redox flow batteries: recent progress and future perspectives

As the population increases sharply around the globe, huge shortages are occurring in energy resources. Renewable resources are urgently required to be developed to satisfy human demands. Unlike the lithium-ion batteries with safety and cost issues, the redox flow battery (RFB) is economical, stable, and convenient for the development of large-scale stationary electrical energy storage applications. Especially, the aqueous redox flow battery (ARFB) further exhibits a promising potential in larger power grids owing to its unique structural features of storing energy by filling the tank with electrolytes. The ARFB is capable of modulating battery parameters by controlling the volume and concentration of the electro-active species (EAS). Further, halogens show excellent properties, such as low cost and appropriate potential as an EAS for ARFB, further showing an efficient, safe, and affordable energy storage system (ESS). Moreover, to attain the demands of strong activity, high sensitivity, convenience as well as practicality, further attention needs to be paid to material (electrode) design and adjustment. In this mini-review, novel electrode materials, including their potential internal mechanisms and effective regulatory means, are summarized and applied in the zinc-halogen, hydrogen-halogen, and polysulfide-halogen ARFB systems, promoting the development of valuable material systems and the innovation of the energy storage/conversion technologies.