The glycolytic enzyme PFKFB3 drives kidney fibrosis through promoting histone lactylation-mediated NF-κB family activation.

Persistently elevated glycolysis in kidney has been demonstrated to promote chronic kidney disease (CKD). However, the underlying mechanism remains largely unclear. Here, we observed that 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), a key glycolytic enzyme, was remarkably induced in kidney proximal tubular cells (PTCs) following ischemia-reperfusion injury (IRI) in mice, as well as in multiple etiologies of patients with CKD. PFKFB3 expression was positively correlated with the severity of kidney fibrosis. Moreover, patients with CKD and mice exhibited increased urinary lactate/creatine levels and kidney lactate, respectively. PTC-specific deletion of PFKFB3 significantly reduced kidney lactate levels, mitigated inflammation and fibrosis, and preserved kidney function in the IRI mouse model. Similar protective effects were observed in mice with heterozygous deficiency of PFKFB3 or those treated with a PFKFB3 inhibitor. Mechanistically, lactate derived from PFKFB3-mediated tubular glycolytic reprogramming markedly enhanced histone lactylation, particularly H4K12la, which was enriched at the promoter of NF-κB signaling genes like Ikbkb, Rela, and Relb, activating their transcription and facilitating the inflammatory response. Further, PTC-specific deletion of PFKFB3 inhibited the activation of IKKß, I κ B α, and p65 in the IRI kidneys. Moreover, increased H4K12la levels were positively correlated with kidney inflammation and fibrosis in patients with CKD. These findings suggest that tubular PFKFB3 may play a dual role in enhancing NF-κB signaling by promoting both H4K12la-mediated gene transcription and its activation. Thus, targeting the PFKFB3-mediated NF-κB signaling pathway in kidney tubular cells could be a novel strategy for CKD therapy.

The Spermine Oxidase/Spermine Axis Coordinates ATG5-Mediated Autophagy to Orchestrate Renal Senescence and Fibrosis.

Decreased plasma spermine levels are associated with kidney dysfunction. However, the role of spermine in kidney disease remains largely unknown. Herein, it is demonstrated that spermine oxidase (SMOX), a key enzyme governing polyamine metabolism, is predominantly induced in tubular epithelium of human and mouse fibrotic kidneys, alongside a reduction in renal spermine content in mice. Moreover, renal SMOX expression is positively correlated with kidney fibrosis and function decline in patients with chronic kidney disease. Importantly, supplementation with exogenous spermine or genetically deficient SMOX markedly improves autophagy, reduces senescence, and attenuates fibrosis in mouse kidneys. Further, downregulation of ATG5, a critical component of autophagy, in tubular epithelial cells enhances SMOX expression and reduces spermine in TGF-ß1-induced fibrogenesis in vitro and kidney fibrosis in vivo. Mechanically, ATG5 readily interacts with SMOX under physiological conditions and in TGF-ß1-induced fibrogenic responses to preserve cellular spermine levels. Collectively, the findings suggest SMOX/spermine axis is a potential novel therapy to antagonize renal fibrosis, possibly by coordinating autophagy and suppressing senescence.

Highly-dispersed 2D NiFeP/CoP heterojunction trifunctional catalyst for efficient electrolysis of water and urea.

The electrocatalytic production of "green hydrogen", such as through the electrolysis of water or urea has been vigorously advocated to alleviate the energy crisis. However, their electrode reactions including oxygen evolution reaction (OER), urea oxidation reaction (UOR), and hydrogen evolution reaction (HER) all suffer from sluggish kinetics, which urgently need catalysts to accelerate the processes. Herein, we design and prepare an OER/UOR/HER trifunctional catalyst by transforming the homemade CoO nanorod into a two-dimensional (2D) ultrathin heterojunction nickel-iron-cobalt hybrid phosphides nanosheet (NiFeP/CoP) via a hydrothermal-phosphorization method. Consequently, a strong electronic interaction was found among the Ni2P/FeP4/CoP heterogeneous interfaces, which regulates the electronic structure. Besides the high mass transfer property of 2D nanosheet, Ni2P/FeP4/CoP displays improved OER/UOR/HER performance. At 10 mA cm-2, the OER overpotential reaches 274 mV in 1.0 M KOH, and the potential of UOR is only 1.389 V in 1.0 M KOH and 0.33 M urea. More strikingly, the two-electrode systems for electrolysis water and urea-assisted electrolysis water assembled by NiFeP/CoP could maintain long-term stability for 35 h and 12 h, respectively. This work may help to pave the way for upcoming research horizons of multifunctional electrocatalysts.

Systemic Immune-Inflammation Index Was Significantly Associated with All-Cause and Cardiovascular-Specific Mortalities in Patients Receiving Peritoneal Dialysis.

Purpose: The prognosis of patients receiving peritoneal dialysis (PD) is associated with inflammation. Systemic immune-inflammation index (SII) is one of inflammatory markers, and the role in predicting clinical outcomes in PD patients is unclear. We aimed to investigate the relationship between the SII and all-cause and cardiovascular-specific mortalities in patients undergoing PD. Patients and Methods: A total of 1419 PD patients from the First Affiliated Hospital of Sun Yat-sen University between January 1, 2007 and December 31, 2019 were retrospectively included at baseline, and the patients were followed up until November 31, 2021. SII was calculated as platelet count×neutrophil count/lymphocyte count. Kaplan-Meier curves and Cox proportional hazards regression models were used to determine the relationship between SII levels and all-cause and cardiovascular-specific mortalities. Results: During follow-up (median period was 42 months), 321 patients died (171 died of cardiovascular disease). With adjustment for the potential confounding factors, each 1-SD increase in the SII was associated with 20.2% increase in all-cause mortality (hazard ratio [HR]: 1.202, 95% confidence interval [CI]: 1.088-1.327, P<0.001) and 28.0% increase in cardiovascular-specific mortality (HR: 1.280, 95% CI: 1.126-1.456, P<0.001). High SII (vs low SII) was significantly associated with increased risks of all-cause mortality (HR: 1.391, 95% CI: 1.066-1.815, P-value: 0.015) and cardiovascular-specific mortality (HR: 1.637, 95% CI: 1.185-2.261, P-value: 0.003). Subgroups analyses showed similar results for those younger than 65-year-old only. Conclusion: Elevated SII level was independently associated with increased risks of all-cause and cardiovascular-specific mortalities in PD patients, especially for those younger than 65-year-old.

Therapeutic mechanism of baicalein in peritoneal dialysis-associated peritoneal fibrosis based on network pharmacology and experimental validation.

Baicalein (5,6,7-trihydroxyflavone) is a traditional Chinese medicine with multiple pharmacological and biological activities including anti-inflammatory and anti-fibrotic effects. However, whether baicalein has a therapeutic impact on peritoneal fibrosis has not been reported yet. In the present study, network pharmacology and molecular docking approaches were performed to evaluate the role and the potential mechanisms of baicalein in attenuating peritoneal dialysis-associated peritoneal fibrosis. The results were validated in both animal models and the cultured human mesothelial cell line. Nine intersection genes among baicalein targets and the human peritoneum RNA-seq dataset including four encapsulating peritoneal sclerosis samples and four controls were predicted by network analysis. Among them, MMP2, BAX, ADORA3, HIF1A, PIM1, CA12, and ALOX5 exhibited higher expression in the peritoneum with encapsulating peritoneal sclerosis compared with those in the control, which might be crucial targets of baicalein against peritoneal fibrosis. Furthermore, KEGG and GO enrichment analyses suggested that baicalein played an anti-peritoneal fibrosis role through the regulating cell proliferation, inflammatory response, and AGE-RAGE signaling pathway. Moreover, molecular docking analysis revealed a strong potential binding between baicalein and MMP2, which was consistent with the predictive results. Importantly, using a mouse model of peritoneal fibrosis by intraperitoneally injecting 4.25% glucose dialysate, we found that baicalein treatment significantly attenuated peritoneal fibrosis, as evident by decreased collagen deposition, protein expression of α-SMA and fibronectin, and peritoneal thickness, at least, by reducing the expression of MMP2, suggesting that baicalein may have therapeutic potential in suppressing peritoneal dialysis-related fibrosis.

Synergistic Effect of N-NiMoO4 /Ni Heterogeneous Interface with Oxygen Vacancies in N-NiMoO4 /Ni/CNTs for Superior Overall Water Splitting.

The exploring of economical, high-efficiency, and stable bifunctional catalysts for hydrogen evolution and oxygen evolution reactions (HER/OER) is highly imperative for the development of electrolytic water. Herein, a 3D cross-linked carbon nanotube supported oxygen vacancy (Vo )-rich N-NiMoO4 /Ni heterostructure bifunctional water splitting catalyst (N-NiMoO4 /Ni/CNTs) is synthesized by hydrothermal-H2 calcination method. Physical characterization confirms that Vo -rich N-NiMoO4 /Ni nanoparticles with an average size of ≈19 nm are secondary aggregated on CNTs that form a hierarchical porous structure. The formation of Ni and NiMoO4 heterojunctions modify the electronic structure of N-NiMoO4 /Ni/CNTs. Benefiting from these properties, N-NiMoO4 /Ni/CNTs drives an impressive HER overpotential of only 46 mV and OER overpotential of 330 mV at 10 mA cm-2 , which also shows exceptional cycling stability, respectively. Furthermore, the as-assembled N-NiMoO4 /Ni/CNTs||N-NiMoO4 /Ni/CNTs electrolyzer reaches a cell voltage of 1.64 V at 10 mA cm-2 in alkaline solution. Operando Raman analysis reveals that surface reconstruction is essential for the improved catalytic activity. Density functional theory (DFT) calculations further demonstrate that the enhanced HER/OER performance should be attributed to the synergistic effect of Vo and heteostructure that improve the conductivity of N-NiMoO4 /Ni/CNTs and facilitatethe desorption of reaction intermediates.

Single-cell sequencing reveals peritoneal environment and insights into fibrosis in CAPD patients.

Long-term peritoneal dialysis (PD) is associated with the development of peritoneal fibrosis (PF). Understanding the changes of immune environments and peritoneal mesothelial cells (PMCs) may lead to the discovery of mechanisms of PF. Therefore, we used single-cell RNA sequencing to interrogate cell composition and transcriptome characteristics in dialysate of continuous ambulatory PD (CAPD) patients at different stages. Results showed that six major cell populations were identified in overnight effluent dialysate. Two subsets of macrophages (Macro-c2-SSP1 and Macro-c5-FCN1&SSP1) and PMCs (HSPA1A + PMCs and RPL34 + PMCs) had the property of promoting fibrosis. Long-term patients had higher markers of cytotoxic CD8+T cells. Moreover, the expression levels of fibrosis-related genes were significantly increased and PMCs interacted closely with immune cells in the long-term group (p < 0.05). These data reveal new phenotypes and functional characteristics of immune cells and PMCs in dialysate of CAPD patients with different stages, which provide potential mechanisms and therapeutic strategies for PF.

Clinical Characteristics and Risk Factors for Mortality in Older Patients with Dialysis-Receiving Community-Acquired Acute Kidney Injury.

INTRODUCTION: Older people in community are susceptible to acute kidney injury (AKI) and hemodialysis is the most important supportive measure used in the management of severe AKI. This study aims to investigate the clinical characteristics, outcomes and risk factors for mortality in older patients with dialysis-receiving-community-acquired AKI (CA-AKI). METHODS: A total of 1953 CA-AKI patients aged 65 years old and above were recruited from 2013 to 2016. Among which, 200 patients received hemodialysis. Clinical characteristics, outcomes, suspected nephrotoxic drug use after CA-AKI and risk factors for mortality in older CA-AKI patients with dialysis were analyzed. RESULTS: The percentage of CA-AKI patients receiving hemodialysis was 10.2%. Compared with non-dialysis patients, dialysis-receiving patients had more comorbidity, and worse renal function. The types of suspected nephrotoxic drugs used in dialysis patients were more than those in non-dialysis patients. Moreover, dialysis-receiving patients had worse outcomes, including complete recovery of renal function (42.0% vs 71.6%), intensive care unit (ICU) (69.0% vs 15.3%) transfer and in-hospital mortality (50.5% vs 5.6%) (P<0.01). Age, moderate/severe liver disease, beta lactam antibiotics, glycopeptide antibiotics, antifungal agents, drugs for anti-heart failure, category of suspected nephrotoxic drugs, hyperkalemia, increased leucocyte count, ICU transfer, multiple organ dysfunction (MODS), cardiogenic shock and cardio-pulmonary resuscitation (CPR) were risk factors for mortality by univariate logistic regression analysis. After adjusting for confounding factors, the independent risk factors were glycopeptide antibiotics, drugs for anti-heart failure, ICU transfer, MODS and CPR. CONCLUSION: The percentage of older CA-AKI patients receiving dialysis was high, and these patients had more comorbidity and worse prognosis. Glycopeptide antibiotics, drugs for anti-heart failure, ICU transfer, MODS and CPR were independent risk factors for mortality.

Hepatitis B Virus-Related Glomerulonephritis with Positive and Negative Serum HBsAg: Different Clinicopathologic Characteristics of Two Clinical Subtypes.

INTRODUCTION: The clinicopathologic characteristics of Hepatitis B virus-associated glomerulonephritis (HBV-GN) patients with different serum HBsAg are not well known. This study aims to investigate the characteristics and treatments between HBV-GN patients with positive and negative serum HBsAg. METHODS: A retrospective review of patients with renal biopsies in Guangdong Provincial People's Hospital from 2005 to 2018 was performed. Clinicopathological data, treatments and remission of proteinuria were collected and compared between HBsAg+ and HBsAg- group. RESULTS: A total of 101 HBV-GN were recruited. Serum HBsAg+ and HBsAg- patients accounted for 62.4% and 37.6%, respectively. HBsAg+ group had poor kidney and liver functions. Pathological data showed the percentage of membranous nephropathy in HBsAg- group is significantly higher than that of HBsAg+ group (60.3% HBsAg+ vs 89.5% HBsAg-, P<0.05). Chronic renal tubular/interstitial injury was more prevalent in HBsAg+ group (16.9% HBsAg+ vs 2.6% HBsAg-, P<0.05). The deposition sites of immune complexes were significant different between the two groups. In addition, more HBsAg+ patients were given anti-HBV and less were given corticosteroid or immunosuppressants for treatment than that of HBsAg- patients. Percentages of clinical remission were increasing in both HBsAg+ and HBsAg- patients from 1, 3, 6 months to 1 year (18.75%, 45.2%, 67.8%, 82.4% vs 24.4%, 41.2%, 62.8%, 59.3%). The differences of remission betwen two groups were not significant (P>0.05). CONCLUSION: The clinicopathological characteristics and treatments of HBV-GN with serum HBsAg+ and HBsAg- were distinct, which indicated that the pathogenesis might be different and specific treatments were needed for HBV-GN patients with different serum HBsAg.

M2 Macrophage Subpopulations in Glomeruli Are Associated With the Deposition of IgG Subclasses and Complements in Primary Membranous Nephropathy.

Objectives: The role of M2 macrophages in the pathogenesis and progression of primary membranous nephropathy (PMN) remains unknown. In this study, we aimed to investigate the relationship between M2 subsets and clinicopathological features of patients with PMN. Methods: A total of 55 patients with PMN confirmed by biopsy were recruited. The clinical and pathological data were recorded, respectively. Immunohistochemistry was used to detect the markers of M2 macrophages, including total macrophages (CD68+), M2a (CD206+), M2b (CD86+) and M2c (CD163+). Results: The numbers of glomerular macrophages, M2a, M2b, and M2c macrophages were 1.83 (1.00, 2.67), 0.65 (0.15, 1.15), 0.67 (0.33, 1.50), and 0.80 (0.05, 2.30) per glomerulus, respectively. Higher number of glomerular macrophages was found in stage II compared with stage III (2.08 vs. 1.16, P = 0.008). These macrophages also were negatively correlated with serum albumin level (r = -0.331, P = 0.014), while positively associated with complement 3 (C3) deposition (r = 0.300, P = 0.026) and the severity of glomerulosclerosis (r = 0.276, P = 0.041). Moreover, glomerular M2a macrophages were significantly correlated with the deposition of C3 (r = 0.300, P = 0.026), immunoglobulin G1 (IgG1) (r = 0.339, P = 0.011), immunoglobulin G2 (IgG2) (r = 0.270, P = 0.046) and immunoglobulin G3 (IgG3) (r = 0.330, P = 0.014) in glomerular basement membrane (GBM). In addition, M2b macrophages were positively associated with IgG1 (r = 0.295, P = 0.029) and IgG2 (r = 0.393, P = 0.003), while M2c macrophages were negatively correlated with complement 4d (C4d) (r = -0.347, P = 0.009) in GBM. Conclusions: Our results showed that M2 macrophage subpopulations in glomeruli are associated with the deposition of IgG subclasses and complements in renal tissue of PMN, which indicate that M2 macrophages may be involved in the pathogenesis and progression of PMN. Moreover, M2a and M2c macrophages might show different tendencies in the pathogenesis of PMN.

Transcription factor PU.1 and immune cell differentiation (Review).

The transcription factor PU.1, an important member of the ETS family, plays a significant role in the differentiation of immune cells, which include macrophages, neutrophils, dendritic cells, T lymphoid cells, B lymphoid cells and so on. Immune cells are involved in the occurrence and development of diseases, including inflammatory diseases, neoplastic diseases and immune diseases. Therefore, it is particularly crucial to elucidate the roles and mechanisms of PU.1 in immune cells. The elucidation of these mechanisms may lead to the development of more effective therapeutic strategies for the treatment of inflammatory diseases and immune­mediated diseases mediated by various immune cells. With the development of molecular biology, the mechanisms of PU.1 in immune cell differentiation have been further explained. Different levels of PU.1 expression determine the type of immune cell differentiation. PU.1 expression is increased during granulocyte and macrophage differentiation, while it is decreased during T lymphocyte and B lymphocyte differentiation. The present study reviews and discusses the effects of the transcription factor PU.1 on immune cell differentiation.

FeNi Alloy Nanoparticles Encapsulated in Carbon Shells Supported on N-Doped Graphene-Like Carbon as Efficient and Stable Bifunctional Oxygen Electrocatalysts.

The development of cost-effective and durable oxygen electrocatalysts remains highly critical but challenging for energy conversion and storage devices. Herein, a novel FeNi alloy nanoparticle core encapsulated in carbon shells supported on a N-enriched graphene-like carbon matrix (denoted as FeNi@C/NG) was constructed by facile pyrolyzing the mixture of metal salts, glucose, and dicyandiamide. The in situ pyrolysis of dicyandiamide in the presence of glucose plays a significant effect on the fabrication of the porous FeNi@C/NG with a high content of doped N and large specific surface area. The optimized FeNi@C/NG catalyst displays not only a superior catalytic performance for the oxygen reduction reaction (ORR, with an onset potential of 1.0 V and half-wave potential of 0.84 V) and oxygen evolution reaction (OER, the potential at 10 mA cm-2 is 1.66 V) simultaneously in alkaline, but also outstanding long-term cycling durability. The excellent bifunctional ORR/OER electrocatalytic performance is ascribed to the synergism of the carbon shell and FeNi alloy core together with the high-content of nitrogen doped on the large specific surface area graphene-like carbon.

A 2D covalent organic framework as a sensor for detecting formaldehyde.

Formaldehyde is the main cause of indoor pollution. In this research, we investigated the mechanism that the covalent organic framework (COF) identifies formaldehyde applying density functional theory (DFT) and time-dependent (TD) DFT approaches. On one hand, the calculation results of the geometric parameters, IR spectra, as well as 1H-NMR chemical shifts for protons that associated with the hydrogen bonding formation together with the electronic transition energies verified that the furcate hydrogen bonding formed between the COF and formaldehyde is enhanced in the excited S1 state and it is not beneficial to luminescence of the COF. On the other hand, excitingly, our further calculation results of the fluorescence rate coefficients also revealed that the strengthened hydrogen bonding behavior in S1 state caused an efficiently weakened luminescent phenomenon compared with that of the COF. Therefore, this analysis method, which qualitative collaborates with quantitative theoretically, demonstrates the possibility that the COF could be served as a sensor to detect formaldehyde. Graphical Abstract The luminescence of the Covalent Organic Framework can be greatly weakened after the addition of formaldehyde.

A recognition mechanism study: Luminescent metal-organic framework for the detection of nitro-explosives.

This article presents a recognition mechanism for nitro-explosives by the luminescent metal-organic framework 1 (LMOF-1) with the aid of density functional theory (DFT) and time-dependent density functional theory (TDDFT). The behavior of hydrogen bonding between the LMOF-1 and nitro-explosives in the S1 state is closely associated with the fluorescence properties of the LMOF-1. In our research, we calculated the geometric configuration, 1H NMR and IR spectra of the Complex 2 formed by LMOF-1 and nitrobenzene in the S0 and S1 states. The results showed that the hydrogen bond in the S1 state was increased, which was unfavorable for the luminescence of LMOF-1. Furthermore, the fluorescence rate of LMOF-1 decreased after encapsulating nitrobenzene into it. These calculated results collectively suggest that LMOF-1 is a potential fluorescence sensor for the detection of nitro-explosives. This research was aiming to provide a better understanding of the recognition mechanism by LMOFs for nitro-explosives.

N/S/B-doped graphitized carbon encased Fe species as a highly active and durable catalyst towards oxygen reduction reaction.

Exploring cost-effective, high-performance and durable non-precious metal catalysts is of great significance for the acceleration of sluggish oxygen reduction reaction (ORR). Here, we report an intriguing heteroatom-doped graphitized carbon encased Fe species composite by introducing N, S and B sequentially. The experimental approach was designed ingeniously for that the FeCl3·6H2O could catalyze thiourea to synthesize N, S co-doped carbon materials which would further react with H3BO3 and NH3 (emerged at the heat-treatment process) to prepare N, S and B co-doped carbon materials (Fe-N/S/B-C). The Fe-N/S/B-C exhibits an impressive ORR activity for its half-wave potential of -0.1 V, which is 36 mV or 19 mV higher than that of the corresponding single or dual doped counterparts (Fe-N-C or Fe-N/S-C) and 31 mV positive than that of Pt/C catalyst, respectively. Further chronoamperometric measurement and accelerated aging test confirm the excellent electrochemical durability of Fe-N/S/B-C with the stable core-shell structure. The remarkable ORR performance and facile preparation method enable Fe-N/S/B-C as a potential candidate in electrochemical energy devices.

TDDFT study on recognition mechanism for the oxygen sensing of the cyclometalated platinum (II) complex.

The influence of oxygen molecule on the luminescent properties of a cyclometalated Pt(II) complex Lxp1, was investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. Analysis of frontier molecular orbitals and electronic configuration indicated that the highest-occupied molecular orbital of the Lxp1 has a significant mixture of metal Pt (d) as well as 2-phenylpyridine and acetyl acetone(π). The lowest-unoccupied orbital of the Lxp1 primarily locates on π* of 2-phenylpyridineligands. The emission mechanism of the cyclometalated Pt(II) complex Lxp1 is assigned to the mixing of ligand-to-metal charge transfer and ligand-to-ligand charge transfer. The emission mechanism of the Lxp1-O2 complex can be attributed to the charge transfer from the oxygen molecule to the luminescent material Lxp1. Our study showed that intermolecular hydrogen bonding between the Lxp1 and oxygen molecule was strengthened by the calculation of electronic excitation, leading to a luminescence-decreasing phenomenon. The calculation of the radiative and non-radiative decay rate constants of the Lxp1 and the Lxp1-O2 complex demonstrates that the phosphorescence from T1-S0 of the Lxp1 would alter to the internal conversion from T1-T0 of the Lxp1-O2 complex. This alteration further explains the luminescence quenching phenomenon of the cyclometalated Pt(II) complex Lxp1 after interacting with oxygen molecule.

Efficient Synthesis of Nitrogen- and Sulfur-co-Doped Ketjenblack with a Single-Source Precursor for Enhancing Oxygen Reduction Reaction Activity.

Promoting the oxygen reduction reaction (ORR) catalytic activities of cost-effective catalysts is of great significance for the development of various energy conversion and storage systems. Herein, we describe the preparation of a highly active N- and S-co-doped ketjenblack (Kb) by facile pyrolysis of a mixture of thiourea and Kb in the presence of FeCl3 ⋅6 H2 O followed by an acid-leaching process. This novel synthetic approach was rationally designed with the consideration that thiourea could easily introduce both N and S heteroatoms into the carbon matrix by a heat-treatment method by releasing plentiful reactive N- and S-containing gases, which could simultaneously optimize the porous structure of the resultant catalyst. Physical characterization revealed that N and S were homogeneously incorporated into the nanostructure of Kb and formed a hierarchical porous structure with a high specific surface area. The N/S-Kb catalyst showed impressive ORR activity, with an onset potential of 0.08 V at 0.1 mA cm-2 , which is 20 mV more positive than that of commercial 20 wt. % Pt/C catalyst. This was coupled with long-term durability and superior methanol tolerance in alkaline media. The improved ORR performance can be mainly ascribed to synergistic contributions of highly efficient active sites arising from high contents of thiophene S and pyridinic N along with the high specific surface area and the favorable mass-transport properties arising from the hierarchical porous structure. The remarkable ORR performance and facile preparation method make the N/S-Kb catalyst a promising substitute for Pt in electrochemical energy devices.

Ionic liquids as precursors for efficient mesoporous iron-nitrogen-doped oxygen reduction electrocatalysts.

A ferrocene-based ionic liquid (Fe-IL) is used as a metal-containing feedstock with a nitrogen-enriched ionic liquid (N-IL) as a compatible nitrogen content modulator to prepare a novel type of non-precious-metal-nitrogen-carbon (M-N-C) catalysts, which feature ordered mesoporous structure consisting of uniform iron oxide nanoparticles embedded into N-enriched carbons. The catalyst Fe(10) @NOMC exhibits comparable catalytic activity but superior long-term stability to 20 wt % Pt/C for ORR with four-electron transfer pathway under alkaline conditions. Such outstanding catalytic performance is ascribed to the populated Fe (Fe3 O4 ) and N (N2) active sites with synergetic chemical coupling as well as the ordered mesoporous structure and high surface area endowed by both the versatile precursors and the synthetic strategy, which also open new avenues for the development of M-N-C catalytic materials.