Improving Room-Temperature Li-Metal Battery Performance by In Situ Creation of Fast Li+ Transport Pathways in a Polymer-Ceramic Electrolyte.

Composite polymer-ceramic electrolytes have shown considerable potential for high-energy-density Li-metal batteries as they combine the benefits of both polymers and ceramics. However, low ionic conductivity and poor contact with electrodes limit their practical usage. In this study, a highly conductive and stable composite electrolyte with a high ceramic loading is developed for high-energy-density Li-metal batteries. The electrolyte, produced through in situ polymerization and composed of a polymer called poly-1,3-dioxolane in a poly(vinylidene fluoride)/ceramic matrix, exhibits excellent room-temperature ionic conductivity of 1.2 mS cm-1 and high stability with Li metal over 1500 h. When tested in a Li|electrolyte|LiFePO4 battery, the electrolyte delivers excellent cycling performance and rate capability at room temperature, with a discharge capacity of 137 mAh g-1 over 500 cycles at 1 C. Furthermore, the electrolyte not only exhibits a high Li+ transference number of 0.76 but also significantly lowers contact resistance (from 157.8 to 2.1 Ω) relative to electrodes. When used in a battery with a high-voltage LiNi0.8 Mn0.1 Co0.1 O2 cathode, a discharge capacity of 140 mAh g-1 is achieved. These results show the potential of composite polymer-ceramic electrolytes in room-temperature solid-state Li-metal batteries and provide a strategy for designing highly conductive polymer-in-ceramic electrolytes with electrode-compatible interfaces.

Simultaneously Improved Surface and Bulk Participation of Evolved Perovskite Oxide for Boosting Oxygen Evolution Reaction Activity Using a Dynamic Cation Exchange Strategy.

Perovskite oxides are intriguing electrocatalysts for the oxygen evolution reaction, but both surface (e.g., composition) and bulk (e.g., lattice oxygen) properties should be optimized to maximize their participation in offering favorable activity and durability. In this work, it is demonstrated that through introducing exogenous Fe3+ ( Fe exo 3 + ${\rm{Fe}}_{{\rm{exo}}}^{3 + }$ ) into the liquid electrolyte, not only is the reconstructed surface stabilized and optimized, but the lattice oxygen diffusion is also accelerated. As a result, compared to that in Fe-free 0.1 m KOH, PrBa0.5 Sr0.5 Co2 O5+δ in 0.1 m KOH + 0.1 mm Fe3+ demonstrates a tenfold increment in activity, an extremely low Tafel slope of ≈50 mV dec-1 , and outstanding stability at 10.0 mA cm-2  for 10 h. The superior activity and stability are further demonstrated in Zn-air batteries by presenting high open-circuit voltage, narrow potential gap, high power output, and long-term cycle stability (500 cycles). Based on experimental and theoretical calculations, it is discovered that the dynamical interaction between the Co hydr(oxy)oxide from surface reconstruction and intentional Fe3+ from the electrolyte plays an important role in the enhanced activity and durability, while the generation of a perovskite-hydr(oxy)oxide heterostructure improves the lattice oxygen diffusion to facilitate lattice oxygen participation and enhances the stability.

Realizing Simultaneous Detrimental Reactions Suppression and Multiple Benefits Generation from Nickel Doping toward Improved Protonic Ceramic Fuel Cell Performance.

Anode-supported protonic ceramic fuel cells (PCFCs) are highly promising and efficient energy conversion systems. However, several challenges need to be overcome before these systems are used more widely, including the poor sintering of recently developed proton-conducting oxides and the decreased proton conductivity due to detrimental reactions between the nickel from anode and the electrolyte occurring during high-temperature co-sintering. Herein, a Ni doping strategy to increase the electrolyte sintering, suppress the detrimental phase reactions, and generate stable Ni nanoparticles for enhanced performance is proposed. A nickel-doped perovskite oxide is developed with the nominal composition of Ba(Zr0.1 Ce0.7 Y0.1 Yb0.1 )0.95 Ni0.05 O3- δ . Acting as a sintering aid, such a small amount of nickel effectively improves the sintering of the electrolyte. Concomitantly, reactions between nickel and the Ni-doped ceramic phase are suppressed, turning detrimental phase reactions into benefits. The nickel doping further promotes the formation of Ni nanoparticles, which enhance the electrocatalytic activity of the anode toward the hydrogen oxidation reaction and improve the charge transfer across the anode-electrolyte interface. As a result, highly efficient PCFCs are developed. The innovative anode developed in this work also shows favorable activity toward ammonia decomposition, making it highly promising for use in direct ammonia fuel cells.

PERSEUS-IT 24-month analysis: a prospective observational study to assess the effectiveness of intravitreal aflibercept in routine clinical practice in Italy in patients with neovascular age-related macular degeneration.

PURPOSE: PERSEUS-IT (NCT02289924) was a prospective, observational, 2-year study evaluating the effectiveness and treatment patterns of intravitreal aflibercept (IVT-AFL) in patients with neovascular age-related macular degeneration (nAMD) in routine clinical practice in Italy. METHODS: Treatment-naïve patients with nAMD receiving IVT-AFL per routine clinical practice were enrolled. The primary endpoint was mean change in visual acuity (VA; decimals) from baseline to month (M) 12 and M24. Outcomes were evaluated for the overall study population and independently for the 2 treatment cohorts: regular (3 initial monthly doses, ≥ 7 injections by M12, and ≥ 4 injections between M12 and M24) and irregular (any other pattern). RESULTS: Of 813 patients enrolled, 709 were included in the full analysis set (FAS); VA assessments were available for 342 patients at M12 (FAS1Y, 140 regular and 202 irregular) and 233 patients at M24 (FAS2Y, 37 regular and 196 irregular). In the overall FAS, the mean ± SD change in VA from baseline to M12 and M24 was + 0.09 ± 0.24 and + 0.02 ± 0.25 decimals, and there was a statistically significant difference between the regular and irregular cohorts in both FAS1Y (p = 0.0034) and FAS2Y (p = 0.0222). Ocular treatment-emergent adverse events were reported in 4.1% (n = 33/810 [safety set]) of patients. CONCLUSION: In PERSEUS-IT, clinically relevant functional and anatomic improvements were observed within the first 12 months of IVT-AFL treatment in routine clinical practice in Italy in patients with treatment-naïve nAMD. These gains were generally maintained across the 2-year study. The safety profile of IVT-AFL was consistent with prior studies. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Identifier: NCT02289924. DATE OF REGISTRATION: November 13, 2014.

Precise Modulation of Triple-Phase Boundaries towards a Highly Functional Exsolved Catalyst for Dry Reforming of Methane under a Dilution-Free System.

Dry reforming of methane (DRM) has been emerging as a viable solution to achieving carbon neutrality enhanced by the Paris Agreement as it converts the greenhouse gases of CO2 and CH4 into industrially useful syngas. However, there have been limited studies on the DRM catalyst under mild operating conditions with a high dilution gas ratio due to their deactivation from carbon coking and metal sintering. Herein, we apply the triple-phase boundary (TPB) concept to DRM catalyst via exsolution phenomenon that can secure elongated TPB by controlling the Fe-doping ratio in perovskite oxide. Remarkably, the exsolved catalyst with prolongated TPB shows exceptional CO2 and CH4 conversion rates of 95.9 % and 91.6 %, respectively, stable for 1000 hours under a dilution-free system. DFT calculations confirm that the Lewis acid of support and Lewis base of metal at the TPB promote the adsorption of reactants, resulting in lowering the overall CO2 dissociation and CH4 dehydrogenation energy.

Enhancing the Intrinsic Activity and Stability of Perovskite Cobaltite at Elevated Temperature Through Surface Stress.

Perovskite-based oxides attract great attention as catalysts for energy and environmental devices. Nanostructure engineering is demonstrated as an effective approach for improving the catalytic activity of the materials. The mechanism for the enhancement, nevertheless, is still not fully understood. In this study, it is demonstrated that compressive strain can be introduced into freestanding perovskite cobaltite La0.8 Sr0.2 CoO3- δ (LSC) nanofibers with sufficient small size. Crystal structure analysis suggests that the LSC fiber is characterized by compressive strain along the ab plane and less distorted CoO6 octahedron compared to the bulk powder sample. Accompanied by such structural changes, the nanofiber shows significantly higher oxygen reduction reaction (ORR) activity and better stability at elevated temperature, which is attributed to the higher oxygen vacancy concentration and suppressed Sr segregation in the LSC nanofibers. First-principle calculations further suggest that the compressive strain in LSC nanofibers effectively shortens the distance between the Co 3d and O 2p band center and lowers the oxygen vacancy formation energy. The results clarify the critical role of surface stress in determining the intrinsic activity of perovskite oxide nanomaterials. The results of this work can help guide the design of highly active and durable perovskite catalysts via nanostructure engineering.

Non-precious-metal catalysts for alkaline water electrolysis: operando characterizations, theoretical calculations, and recent advances.

Recent years have witnessed an upsurge in the development of non-precious catalysts (NPCs) for alkaline water electrolysis (AWE), especially with the strides made in experimental and computational techniques. In this contribution, the most recent advances in NPCs for AWE were systematically reviewed, emphasizing the application of in situ/operando experimental methods and density functional theory (DFT) calculations in their understanding and development. First, we briefly introduced the fundamentals of the anode and cathode reaction for AWE, i.e., the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), respectively. Next, the most popular in situ/operando approaches for characterizing AWE catalysts, including hard and soft XAS, ambient-pressure XPS, liquid and identical location TEM, electrochemical mass spectrometry, and Raman spectroscopy were thoroughly summarized. Subsequently, we carefully discussed the principles, computational methods, applications, and combinations of DFT with machine learning for modeling NPCs and predicting the alkaline OER and HER. With the improved understanding of the structure-property-performance relationship of NPCs for AWE, we proceeded to overview their current development, summarising state-of-the-art design strategies to boost their activity. In addition, advances in various extensively investigated NPCs for AWE were evaluated. By conveying these methods, progress, insights, and perspectives, this review will contribute to a better understanding and rational development of non-precious AWE electrocatalysts for hydrogen production.

Sodiophilically Graded Gold Coating on Carbon Skeletons for Highly Stable Sodium Metal Anodes.

Metallic sodium (Na) is an appealing anode material for high-energy Na batteries. However, Na metal suffers from low coulombic efficiencies and severe dendrite growth during plating/stripping cycles, causing short circuits. As an effective strategy to improve the deposition behavior of Na metal, a 3D carbon foam is developed that is sputter-coated with gold nanoparticles (Au/CF), forming a functional gradient through its thickness. The highly porous Au/CF host is proven to have gradually varying sodiophilicity, which in turn facilitates initially preferential Na deposition on the gold-rich, sodiophilic region in a "bottom-up growth" mode, leading to uniform plating over the entire Au/CF host. This finding contrasts with dendrite formation in the pristine CF host, as proven by in situ microscopy. The Na-predeposited Au/CF (Na@Au/CF) composite anode operates steadily for 1000 h at a low overpotential of ≈20 mV at 2 mA cm-2 in a symmetric cell. When the composite anode is coupled with a Na3 V2 (PO4 )2 F3 cathode, the full cell has a high capacity of 102.1 mAh g-1 after 500 cycles at 2 C. The sodiophilicity gradient design that is explored in this study offers new insight into developing porous Na metal hosts with highly stable plating/stripping performance for next-generation Na batteries.

Molybdenum Disulfide Based Nanomaterials for Rechargeable Batteries.

The rapid development of electrochemical energy storage systems requires new electrode materials with high performance. As a two-dimensional material, molybdenum disulfide (MoS2 ) has attracted increasing interest in energy storage applications due to its layered structure, tunable physical and chemical properties, and high capacity. In this review, the atomic structures and properties of different phases of MoS2 are first introduced. Then, typical synthetic methods for MoS2 and MoS2 -based composites are presented. Furthermore, the recent progress in the design of diverse MoS2 -based micro/nanostructures for rechargeable batteries, including lithium-ion, lithium-sulfur, sodium-ion, potassium-ion, and multivalent-ion batteries, is overviewed. Additionally, the roles of advanced in situ/operando techniques and theoretical calculations in elucidating fundamental insights into the structural and electrochemical processes taking place in these materials during battery operation are illustrated. Finally, a perspective is given on how the properties of MoS2 -based electrode materials are further improved and how they can find widespread application in the next-generation electrochemical energy-storage systems.

Boosting Bifunctional Oxygen Electrolysis for N-Doped Carbon via Bimetal Addition.

The addition of transition metals, even in a trace amount, into heteroatom-doped carbon (M-N/C) is intensively investigated to further enhance oxygen reduction reaction (ORR) activity. However, the influence of metal decoration on the electrolysis of the reverse reaction of ORR, that is, oxygen evolution reaction (OER), is seldom reported. Moreover, further improving the bifunctional activity and corrosion tolerance for carbon-based materials remains a big challenge, especially in OER potential regions. Here, bimetal-decorated, pyridinic N-dominated large-size carbon tubes (MM'-N/C) are proposed for the first time as highly efficient and durable ORR and OER catalysts. FeFe-N/C, CoCo-N/C, NiNi-N/C, MnMn-N/C, FeCo-N/C, NiFe-N/C, FeMn-N/C, CoNi-N/C, MnCo-N/C, and NiMn-N/C are systematically investigated in terms of their structure, composition, morphology, surface area, and active site densities. In contrast to conventional monometal and N-decorated carbon, small amounts of bimetal (≈2 at%) added during the one-step template-free synthesis contribute to increased pyridinic N content, much longer and more robust carbon tubes, reduced metal particle size, and stronger coupling between the encapsulated metals and carbon support. The synergy of those factors accounts for the dramatically improved ORR and OER activity and stability. By comparison, NiFe-N/C and MnCo-N/C stand out and achieve superior bifunctional oxygen catalytic performance, exceeding most of state-of-the-art catalysts.

Modeling the impedance spectra of mixed conducting thin films with exposed and embedded current collectors.

In this article, we develop a new finite-element-based model for the simulation of the electrochemical impedance spectroscopy (EIS) response of mixed ionic electronic conducting (MIEC) thin films. We first validated the model against experimental data for Sm-doped CeO2 (SDC) symmetrical films deposited on an yittria-stabilized ZrO2 (YSZ) substrate, a pure ionic conductor. We first studied the configuration where the patterned electrodes are placed on top of the MIEC ("exposed" configuration). Our model is capable of correctly reproducing the EIS response and the total capacitance, together with their dependence on the oxygen partial pressure. Furthermore, we were able to show, in agreement with experiments, that the area specific resistance (Rp) is relatively insensitive to the density of triple phase boundaries. As a second step, we studied the configuration where the metal current collector is directly deposited on the ionic conductor and is, therefore, "embedded" into the MIEC. We were again able to reproduce the experimental EIS response. We also discovered that at sufficiently high frequencies, the EIS deviates from a traditional RC-type response, leading to features attributable to the coupling ionic and electronic transport. This coupling ultimately adds to the area specific resistance. The latter, however, can be minimized if the film is sufficiently thick or if the current collector configuration is chosen judiciously.

A molecular dynamics study of oxygen ion diffusion in A-site ordered perovskite PrBaCo(2)O(5.5): data mining the oxygen trajectories.

Molecular dynamics (MD) simulations have been widely used to study oxygen ion diffusion in crystals. In the data analysis, one typically calculates the mean squared displacements to obtain the self-diffusion coefficients. Further information extraction for each individual atom poses significant challenges due to the lack of general methods. In this work, oxygen ion diffusion in A-site ordered perovskite PrBaCo2O5.5 is studied using MD simulations and the oxygen migration is analyzed by k-means clustering, a machine learning algorithm. The clustering analysis allows the tracking of each individual oxygen jump along with its corresponding location, i.e., oxygen site in BaO, PrO0.5 and CoO2 layers. Therefore it increases the understanding of the factors influencing oxygen diffusion. For example, it is found that the oxygen occupation fraction in the PrO0.5 layers increases with temperature, while in the CoO2 layers it decreases with temperature. Additionally, the activation enthalpies of oxygen jumps from CoO2 to CoO2, CoO2 to PrO0.5 and PrO0.5 to CoO2 are 0.22 eV, 0.54 eV and 0.34 eV, respectively, exhibiting anisotropic characteristics. Furthermore, the dwell times of oxygen atoms suggest that they are highly mobile in PrO0.5 layers. Combining the analysis of activation enthalpies and dwell times, it is suggested that the oxygen transport is fast within the CoO2 layers while the PrO0.5 layers work as oxygen vacancy reservoirs.

Unraveling the effect of La A-site substitution on oxygen ion diffusion and oxygen catalysis in perovskite BaFeO3 by data-mining molecular dynamics and density functional theory.

BaFeO3 (BFO) is a promising parent material for high-temperature oxygen catalysis. The effects of La substitution on the oxygen ion diffusion and oxygen catalysis in A-site La-substituted BFO are studied by combining data-driven molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The data-driven MD simulations are capable of providing atomic level information regarding oxygen jumps at different sites, bridging the resolution gap of analysis between MD and DFT. The simulations identify several effects due to the introduction of La. First, according to simple electroneutrality considerations and DFT calculations, La tends to decrease the concentration of oxygen vacancies in BFO. Second, La substitution lowers the activation energy of local oxygen migration, providing faster paths for oxygen diffusion. The MD analysis predicts a higher hopping rate through La-containing bottlenecks as well as easier oxygen jumps from the La-rich cages and lower dwell times of oxygen in those cages. DFT calculations confirm a lower migration energy through La-containing bottlenecks. Third, the electrocatalytic activity of the material decreases with La, as indicated by a lower O p-band center and higher oxygen vacancy formation energies.

A DFT+U study of A-site and B-site substitution in BaFeO3-δ.

BaFeO3-δ (BFO)-based perovskites have emerged as cheap and effective oxygen electrocatalysts for oxygen reduction reaction at high temperatures. The BFO cubic phase facilitates a high oxygen deficiency and is commonly stabilised by partial substitution. Understanding the electronic mechanisms of substitution and oxygen deficiency is key to rational material design, and can be realised through DFT analysis. In this work an in-depth first principle DFT+U study is undertaken to determine site distinctive characteristics for 12.5%, Y, La and Ce substitutions in BFO. In particular, it is shown that B-site doped structures exhibit a lower energy cost for oxygen vacancy formation relative to A site doping and pristine BFO. This is attributed to the stabilisation of holes in the oxygen sub-lattice and increased covalency of the Fe-O bonds of the FeO6 octahedra in B-site-substituted BFO. Charge analysis shows that A-site substitution amounts to donor doping and consequently impedes the accommodation of other donors (i.e. oxygen vacancies). However, A-site substitution may also exhibit a higher electronic conductivity due to less lattice distortion for oxygen deficiency compared to B-site doped structures. Furthermore, analysis of the local structural effects provides physical insight into stoichiometric expansions observed for this material.

Defect chemistry and lithium transport in Li3OCl anti-perovskite superionic conductors.

Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10(-3) S cm(-1) at room temperature, among the highest reported values to date. In this work, we investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using ab initio density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.

Modeling the impedance response of mixed-conducting thin film electrodes.

In this paper a novel numerical impedance model is developed for mixed-conducting thin films working as electrodes for solid oxide fuel cells. The relative importance of interfaces is considered by incorporating double layer contributions at the film/gas boundary. Simulations are performed on a model system, namely doped ceria, in a symmetric cell configuration using geometrically well-defined patterned metal current collectors. Results reveal that experimentally consistent bulk impedances and surface capacitances can be extracted using the model. The impedance response depends strongly on the pattern spacing of the current collector, and is attributed to the electronic in-plane drift-diffusion as well as to the interplay between the surface reaction resistance and the electronic/ionic bulk drift-diffusion resistance.

Synergistic Bulk and Surface Engineering for Expeditious and Durable Reversible Protonic Ceramic Electrochemical Cells Air Electrode.

Reversible protonic ceramic electrochemical cells (R-PCECs) offer the potential for high-efficiency power generation and green hydrogen production at intermediate temperatures. However, the commercial viability of R-PCECs is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) within conventional air electrodes operating at reduced temperatures. To address this challenge, this work introduces a novel approach based on the simultaneous optimization of bulk-phase metal-oxygen bonds and in-situ formation of a metal oxide nano-catalyst surface modification. This strategy is designed to expedite the ORR/OER electrocatalytic activity of air electrodes exhibiting triple (O2-, H+, e-) conductivity. Specifically, this engineered air electrode nanocomposite-Ba(Co0.4Fe0.4Zr0.1Y0.1)0.95Ni0.05F0.1O2.9-δ demonstrates remarkable ORR/OER catalytic activity and exceptional durability in R-PCECs. This is evidenced by significantly improved peak power density from 626 to 996 mW cm-2 and highly stable reversibility over a 100-h cycling period. This research offers a rational design strategy to achieve high-performance R-PCEC air electrodes with superior operational activity and stability for efficient and sustainable energy conversion and storage.

Ultra-fast green hydrogen production from municipal wastewater by an integrated forward osmosis-alkaline water electrolysis system.

Recent advancements in membrane-assisted seawater electrolysis powered by renewable energy offer a sustainable path to green hydrogen production. However, its large-scale implementation faces challenges due to slow power-to-hydrogen (P2H) conversion rates. Here we report a modular forward osmosis-water splitting (FOWS) system that integrates a thin-film composite FO membrane for water extraction with alkaline water electrolysis (AWE), denoted as FOWSAWE. This system generates high-purity hydrogen directly from wastewater at a rate of 448 Nm3 day-1 m-2 of membrane area, over 14 times faster than the state-of-the-art practice, with specific energy consumption as low as 3.96 kWh Nm-3. The rapid hydrogen production rate results from the utilisation of 1 M potassium hydroxide as a draw solution to extract water from wastewater, and as the electrolyte of AWE to split water and produce hydrogen. The current system enables this through the use of a potassium hydroxide-tolerant and hydrophilic FO membrane. The established water-hydrogen balance model can be applied to design modular FO and AWE units to meet demands at various scales, from households to cities, and from different water sources. The FOWSAWE system is a sustainable and an economical approach for producing hydrogen at a record-high rate directly from wastewater, marking a significant leap in P2H practice.

Effects of emissions caps on the costs and feasibility of low-carbon hydrogen in the European ammonia industry.

The European ammonia industry emits 36 million tons of carbon dioxide annually, primarily from steam methane reforming (SMR) hydrogen production. These emissions can be mitigated by producing hydrogen via water electrolysis using dedicated renewables with grid backup. This study investigates the impact of decarbonization targets for hydrogen synthesis on the economic viability and technical feasibility of retrofitting existing European ammonia plants for on-site, semi-islanded electrolytic hydrogen production. Results show that electrolytic hydrogen cuts emissions, on average, by 85% (36%-100% based on grid price and carbon intensity), even without enforcing emission limits. However, an optimal lifespan average well-to-gate emission cap of 1 kg carbon dioxide equivalent (CO2e)/kg H2 leads to a 95% reduction (92%-100%) while maintaining cost-competitiveness with SMR in renewable-rich regions (mean levelized cost of hydrogen (LCOH) of 4.1 euro/kg H2). Conversely, a 100% emissions reduction target dramatically increases costs (mean LCOH: 6.3 euro/kg H2) and land area for renewables installations, likely hindering the transition to electrolytic hydrogen in regions with poor renewables and limited land. Increasing plant flexibility effectively reduces costs, particularly in off-grid plants (mean reduction: 32%). This work guides policymakers in defining cost-effective decarbonization targets and identifying region-based strategies to support an electrolytic hydrogen-fed ammonia industry.

Real-world experience with fluocinolone acetonide intravitreal implant in patients with diabetic macular edema.

OBJECTIVES: to evaluate long-term effectiveness and safety of fluocinolone acetonide (FAc) implant used as second-line treatment in patients with persistent diabetic macular edema (DME). METHODS: retrospective data chart review of 241 pseudophakic eyes of 178 patients treated with FAc from July 2017 to December 2021 in 10 medical retinal units in Italy. The primary endpoint was the change of best-corrected visual acuity (BCVA) and central macular thickness (CMT) at 2 years. A Student's paired t-test was used. Additional therapies for DME and intraocular pressure (IOP)-related events were also evaluated. RESULTS: efficacy of FAc was assessed in a subset of 111 eyes with at least 24 months of follow-up. Mean BCVA increased at 2 years by 5.1 ETDRS letters (95%CI = 2.6-7.5; p < 0.001) while mean CMT decreased by 189 µm (95% CI 151-227; p < 0.001). Thirty-eight of these eyes (34.2%) needed additional intravitreal treatments, mainly anti-VEGF. Safety was evaluated on the entire cohort of 241 eyes treated with FAc. Overall, 66 eyes (27.4%) required emergent IOP-lowering medications (typically within the first-year post FAc) while 14 eyes (5.8%) underwent trabeculectomy, mostly during the second year of follow-up. CONCLUSION: FAc implant provides a substantial long-term functional and anatomical benefit when used as second-line treatment in eyes with DME. IOP rise can be adequately managed with topical agents although some eyes may require IOP-lowering surgery.