Self-assembled CoSe2-FeSe2 heteronanoparticles along the carbon nanotube network for boosted oxygen evolution reaction

Hollow CoNiFe ternary metal selenide electrocatalysts derived from Prussian blue analogues for boosting the oxygen evolution reaction

The development of effective electrocatalysts is a top priority for the oxygen evolution reaction (OER), which is the crucial half-reaction of water electrolysis, since electrocatalytic water splitting for hydrogen production offers a practical solution to the upcoming energy crisis. Herein, we report a strategy to fabricate hollow ternary metal selenide (CoNiFe-Se) nanocubes derived from Prussian blue analogues (PBAs) by phytic acid etching and low-temperature gas-phase selenization. Due to the advantages of its multi-component composition and hollow structure, CoNiFe-Se exhibited a low overpotential of 275 mV@10 mA cm-2, a small Tafel slope of 62.3 mV dec-1 and a long-term stability of more than 80 h in 1.0 M KOH. This research offers an innovative idea and a straightforward technique for preparing hollow multimetallic selenide electrocatalysts derived from PBAs.

Advancements in Rechargeable Zn-Air Batteries with Transition-Metal Dichalcogenides as Bifunctional Electrocatalyst

This review covers recent progress on transition metal dichalcogenides (TMDs) as bifunctional electrocatalysts for Zinc-air batteries (ZABs), emphasizing their suitable surface area, electrocatalytic active sites, stability in acidic/basic environments, and tunable electronic properties. It discusses strategies like defect engineering, doping, interface, and structural modifications of TMDs nanostructures for enhancing the performances of ZABs. Zinc-air batteries are promising energy storage devices owing to their high energy density, low cost, and environmental friendliness. However, the development of durable and efficient bifunctional electrocatalysts is a major concern for Zn-air batteries. In this review, we summarize the recent progress on transition metal dichalcogenides (TMDs) as bifunctional electrocatalysts for Zn-air batteries. We discuss the advantages of TMDs, such as high activity, good stability, and tunable electronic structure, as well as the challenges, such as low conductivity, poor durability, and limited active sites. We also highlight the strategies for fine-tuning the properties of TMDs, such as defect engineering, doping, hybridization, and structural engineering, to enhance their catalytic performance and stability. We provide a comprehensive and in-depth analysis of the applications of TMDs in Zn-air batteries, demonstrating their potential as low-cost, abundant, and environmentally friendly alternatives to noble metal catalysts. We also suggest future directions like exploring new TMDs materials and compositions, developing novel synthesis and modification techniques, investigating the interfacial interactions and charge transfer processes, and integrating TMDs with other functional materials. This review aims to illuminate the path forward for the development of efficient and durable Zn-air batteries, aligning with the broader objectives of sustainable energy solutions.

Interfacial Se-O Bonds Modulating Spatial Charge Distribution in FeSe2/Nb:Fe2O3 with Rapid Hole Extraction for Efficient Photoelectrochemical Water Oxidation

Surface engineering is an effective strategy to improve the photoelectrochemical (PEC) catalytic activity of hematite, and the defect states with abundant coordinative unsaturation atoms can serve as anchoring sites for constructing intimate connections between semiconductors. On this basis, we anchored an ultrathin FeSe2 layer on Nb5+-doped Fe2O3 (FeSe2/Nb:Fe2O3) via interfacial Se-O chemical bonds to tune the surface potential. Density functional theory (DFT) calculations indicate that amorphous FeSe2 decoration could generate electron delocalization over the composite photoanodes so that the electron mobility was improved to a large extent. Furthermore, electrons could be transferred via the newly formed Se-O bonds at the interface and holes were collected at the surface of electrode for PEC water oxidation. The desired charge redistribution is in favor of suppressing charge recombination and extracting effective holes. Later, work function calculations and Mott-Schottky (M-S) plots demonstrate that a type-II heterojunction was formed in FeSe2/Nb:Fe2O3, which further expedited carrier separation. Except for spatial carrier modulation, the amorphous FeSe2 layer also provided abundant active sites for intermediates adsorption according to the d band center results. In consequence, the target photoanodes attained an improved photocurrent density of 2.42 mA cm-2 at 1.23 V versus the reversible hydrogen electrode (RHE), 2.5 times as that of the bare Fe2O3. This study proposed a defect-anchoring method to grow a close-connected layer via interfacial chemical bonds and revealed the spatial charge distribution effects of FeSe2 on Nb:Fe2O3, giving insights into rational designation in composite photoanodes.

Room-Temperature Synthesis of Carbon-Nanotube-Interconnected Amorphous NiFe-Layered Double Hydroxides for Boosting Oxygen Evolution Reaction

The oxygen evolution reaction (OER) is a key half-reaction in electrocatalytic water splitting. Large-scale water electrolysis is hampered by commercial noble-metal-based OER electrocatalysts owing to their high cost. To address these issues, we present a facile, one-pot, room-temperature co-precipitation approach to quickly synthesize carbon-nanotube-interconnected amorphous NiFe-layered double hydroxides (NiFe-LDH@CNT) as cost-effective, efficient, and stable OER electrocatalysts. The hybrid catalyst NiFe-LDH@CNT delivered outstanding OER activity with a low onset overpotential of 255 mV and a small Tafel slope of 51.36 mV dec-1, as well as outstanding long-term stability. The high catalytic capability of NiFe-LDH@CNT is associated with the synergistic effects of its room-temperature synthesized amorphous structure, bi-metallic modulation, and conductive CNT skeleton. The room-temperature synthesis can not only offer economic feasibility, but can also allow amorphous NiFe-LDH to be obtained without crystalline boundaries, facilitating long-term stability during the OER process. The bi-metallic nature of NiFe-LDH guarantees a modified electronic structure, providing additional catalytic sites. Simultaneously, the highly conductive CNT network fosters a nanoporous structure, facilitating electron transfer and O2 release and enriching catalytic sites. This study introduces an innovative approach to purposefully design nanoarchitecture and easily synthesize amorphous transition-metal-based OER catalysts, ensuring their cost effectiveness, production efficiency, and long-term stability.

Reversely Trapping Isolated Atoms in High Oxidation State for Accelerating the Oxygen Evolution Reaction Kinetics

Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is paramount to the energy conversion and storage devices. However, the structural complexity of heterogeneous electrocatalysts makes it a great challenge to elucidate the dynamic structural evolution and OER mechanisms. Here, we develop a controllable atom-trapping strategy to extract isolated Mo atom from the amorphous MoOx -decorated CoSe2 (a-MoOx @CoSe2 ) pre-catalyst into Co-based oxyhydroxide (Mo-CoOOH) through an ultra-fast self-reconstruction process during the OER process. This conceptual advance has been validated by operando characterizations, which reveals that the initially rapid Mo leaching can expedite the dynamic reconstruction of pre-catalyst, and simultaneously trap Mo species in high oxidation state into the lattice of in situ generated CoOOH support. Impressively, the OER kinetics of CoOOH has been greatly accelerated after the reverse decoration of Mo species, in which the Mo-CoOOH affords a markedly decreased overpotential of 297 mV at the current density of 100 mA cm-2 . Density functional theory (DFT) calculations demonstrate that the Co species have been greatly activated via the effective electron coupling with Mo species in high oxidation state. These findings open new avenues toward directly synthesizing atomically dispersed electrocatalysts for high-efficiency water splitting.

Facile Electron Transfer in Atomically Coupled Heterointerface for Accelerated Oxygen Evolution

An efficient and cost-effective approach for the development of advanced catalysts has been regarded as a sustainable way for green energy utilization. The general guideline to design active and efficient catalysts for oxygen evolution reaction (OER) is to achieve high intrinsic activity and the exposure of more density of the interfacial active sites. The heterointerface is one of the most attractive ways that plays a key role in electrochemical water oxidation. Herein, atomically cluster-based heterointerface catalysts with strong metal support interaction (SMSI) between WMn₂ O₄ and TiO₂ are designed. In this case, the WMn₂ O₄ nanoflakes are uniformly decorated by TiO₂ particles to create electronic effect on WMn₂ O₄ nanoflakes as confirmed by X-ray absorption near edge fine structure. As a result, the engineered heterointerface requires an OER onset overpotential as low as 200 mV versus reversible hydrogen electrode, which is stable for up to 30 h of test. The outstanding performance and long-term durability are due to SMSI, the exposure of interfacial active sites, and accelerated reaction kinetics. To confirm the synergistic interaction between WMn₂ O₄ and TiO₂ , and the modification of the electronic structure, high-resolution transmission electron microscopy (HR-TEM), X-ray photoemission spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) are used.

Metal-Organic Framework-Derived Fe-Doped Ni3Se4/NiSe2 Heterostructure-Embedded Mesoporous Tubes for Boosting Oxygen Evolution Reaction

It is crucial but challenging to promote sluggish kinetics of oxygen evolution reaction (OER) for water splitting via finely tuning the hierarchical nanoarchitecture and electronic structure of the catalyst. To address such issues, herein we present iron-doped Ni₃Se₄/NiSe₂ heterostructure-embedded metal-organic framework-derived mesoporous tubes (Ni-MOF-Fe-Se-400) realized by an interfacial engineering strategy. Due to the hierarchical nanoarchitecture of conductive two-dimensional nanosheet-constructed MOF-derived mesoporous tubes, coupled with fine tuning of the electronic structure via Fe-doping and interactions between Ni₃Se₄/NiSe₂ heterostructures, the Ni-MOF-Fe-Se-400 catalyst delivers superior OER activity: it requires only a low overpotential of 242 mV to achieve 10 mA cm^-2 (E_j=10), surpassing the benchmark RuO₂ (E_j=10 = 286 mV) and displays exceptional durability in the chronoamperometric i-t test with a small current decay (6.2%) after 72 h. Furthermore, the water splitting system comprises a Ni-MOF-Fe-Se-400 anode and a Pt/C cathode requires a low cell voltage of 1.576 V to achieve E_j=10 with an excellent Faradic efficiency (∼100%), outperforming the RuO₂-Pt/C combination. This work presents a novel interfacial engineering strategy to finely adjust the morphology and electronic structure of the non-noble metal-based OER catalyst via a facile fabrication method.

Spatial Relation Controllable Di-Defects Synergy Boosts Electrocatalytic Hydrogen Evolution Reaction over VSe2 Nanoflakes in All pH Electrolytes

Defect engineering of transition metal dichalcogenides (TMDCs) is important for improving electrocatalytic hydrogen evolution reaction (HER) performance. Herein, a facile and scalable atomic-level di-defect strategy over thermodynamically stable VSe₂ nanoflakes, yielding attractive improvements in the electrocatalytic HER performance over a wide electrolyte pH range is reported. The di-defect configuration with controllable spatial relation between single-atom (SA) V defects and single Se vacancy defects effectively triggers the electrocatalytic HER activity of the inert VSe₂ basal plane. When employed as a cathode, this di-defects decorated VSe₂ electrocatalyst requires overpotentials of 67.2, 72.3, and 122.3 mV to reach a HER current density of 10 mA cm^-2 under acidic, alkaline, and neutral conditions, respectively, which are superior to most previously reported non-noble metal HER electrocatalysts. Theoretical calculations reveal that the reactive microenvironment consists of two adjacent SA Mo atoms with two surrounding symmetric Se vacancies, yielding optimal water dissociation and hydrogen desorption kinetics. This study provides a scalable strategy for improving the electrocatalytic activity of other TMDCs with inert atoms in the basal plane.

Construction of Macroporous Co2SnO4 with Hollow Skeletons as Anodes for Lithium-Ion Batteries

Increasing the energy density of lithium-ion batteries (LIBs) can broaden their applications in energy storage but remains a formidable challenge. Herein, with polyacrylic acid (PAA) as phase separation agent, macroporous Co₂SnO₄ with hollow skeletons was prepared by sol-gel method combined with phase separation. As the anode of LIBs, the macroporous Co₂SnO₄ demonstrates high capacity retention (115.5% at 200 mA·g⁻¹ after 300 cycles), affording an ultrahigh specific capacity (921.8 mA h·g⁻¹ at 1 A·g⁻¹). The present contribution provides insight into engineering porous tin-based materials for energy storage.

Implantable Doppler Probe as a Vascular Monitoring Device in Kidney Transplant Patients: Investigation of Use at a Single Center

OBJECTIVES

Vascular complications account for 30% to 35% of total kidney grafts lost during the first 3 months posttransplant. Early detection of vascular complications allows an opportunity for prompt intervention, which is critical to reducing graft loss. In this study, we evaluated the usefulness of an implantable Doppler probe as a vascular monitoring device in kidney transplant patients.

MATERIALS AND METHODS

An implantable Doppler probe is used intermittently for postoperative monitoring of kidney transplant patients at our center. In this retrospective study, we analyzed prospectively maintained medical data in which we compared clinical outcomes of kidney transplant recipients who had postoperative implantable Doppler probe monitoring versus standard care clinical observation. Between January 2016 and October 2021, 324 kidney transplant patients were seen at our center. Patients were divided into 2 groups: group 1 (n = 194; 60%) included kidney transplant recipients with postoperative implantable Doppler probe monitoring and group 2 (n = 129; 40%) included kidney transplant recipients with standard care clinical observation. We compared number of vascular complications, number of departmental ultrasonographic scans required posttransplant, and graftloss at 3 months between the 2 groups.

RESULTS

Vascular complications were identified in 13.5% of total patients, with graft loss identified in 2.1%. Both groups were similar in demographical characteristics. Group 1 had more vascular complications (17.5% vs 9.3%; relative risk = 1.88), fewer ultrasonographic scans during the first 24 hours posttransplant (71.1% vs 83.7%; relative risk = 0.84), and lower graft loss (1.5% vs 3.1%; relative risk = 0.48) than group 2. All probes were removed safely after 72 hours, and no complications related to the device were reported.

CONCLUSIONS

The monitoring device may be used as an additional adjunct for graft monitoring in kidney transplant patients. Further controlled studies are warranted to evaluate this device in clinical practice.