Artificial nanovesicles for dsRNA delivery in spray-induced gene silencing for crop protection.

Spray-induced gene silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of RNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for RNA encapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP and DODMA, and examined for their ability to protect and deliver double stranded RNA (dsRNA). All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome RNA instability in SIGS for crop protection.

Rice siR109944 suppresses plant immunity to sheath blight and impacts multiple agronomic traits by affecting auxin homeostasis.

Plant small RNAs (sRNAs) play significant roles in regulating various developmental processes and hormone signalling pathways involved in plant responses to a wide range of biotic and abiotic stresses. However, the functions of sRNAs in response to rice sheath blight remain unclear. We screened rice (Oryza sativa) sRNA expression patterns against Rhizoctonia solani and found that Tourist-miniature inverted-repeat transposable element (MITE)-derived small interfering RNA (siRNA) (here referred to as siR109944) expression was clearly suppressed upon R. solani infection. One potential target of siR109944 is the F-Box domain and LRR-containing protein 55 (FBL55), which encode the transport inhibitor response 1 (TIR1)-like protein. We found that rice had significantly enhanced susceptibility when siR109944 was overexpressed, while FBL55 OE plants showed resistance to R. solani challenge. Additionally, multiple agronomic traits of rice, including root length and flag leaf inclination, were affected by siR109944 expression. Auxin metabolism-related and signalling pathway-related genes were differentially expressed in the siR109944 OE and FBL55 OE plants. Importantly, pre-treatment with auxin enhanced sheath blight resistance by affecting endogenous auxin homeostasis in rice. Furthermore, transgenic Arabidopsis overexpressing siR109944 exhibited early flowering, increased tiller numbers, and increased susceptibility to R. solani. Our results demonstrate that siR109944 has a conserved function in interfering with plant immunity, growth, and development by affecting auxin homeostasis in planta. Thus, siR109944 provides a genetic target for plant breeding in the future. Furthermore, exogenous application of indole-3-acetic acid (IAA) or auxin analogues might effectively protect field crops against diseases.

Spray-induced gene silencing for disease control is dependent on the efficiency of pathogen RNA uptake.

Recent discoveries show that fungi can take up environmental RNA, which can then silence fungal genes through environmental RNA interference. This discovery prompted the development of Spray-Induced Gene Silencing (SIGS) for plant disease management. In this study, we aimed to determine the efficacy of SIGS across a variety of eukaryotic microbes. We first examined the efficiency of RNA uptake in multiple pathogenic and non-pathogenic fungi, and an oomycete pathogen. We observed efficient double-stranded RNA (dsRNA) uptake in the fungal plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani, Aspergillus niger and Verticillium dahliae, but no uptake in Colletotrichum gloeosporioides, and weak uptake in a beneficial fungus, Trichoderma virens. For the oomycete plant pathogen, Phytophthora infestans, RNA uptake was limited and varied across different cell types and developmental stages. Topical application of dsRNA targeting virulence-related genes in pathogens with high RNA uptake efficiency significantly inhibited plant disease symptoms, whereas the application of dsRNA in pathogens with low RNA uptake efficiency did not suppress infection. Our results have revealed that dsRNA uptake efficiencies vary across eukaryotic microbe species and cell types. The success of SIGS for plant disease management can largely be determined by the pathogen's RNA uptake efficiency.

Deep Sequencing Uncovers Rice Long siRNAs and Its Involvement in Immunity Against Rhizoctonia solani.

Small RNA (sRNA) is a class of noncoding RNA that can silence the expression of target genes. In rice, the majority of characterized sRNAs are within the range of 21 to 24 nucleotides (nt) long, whose biogenesis and function are associated with a specific sets of components, such as Dicer-like (OsDCLs) and Argonaute proteins (OsAGOs). Rice sRNAs longer than 24 nt are occasionally reported, with biogenesis and functional mechanism uninvestigated, especially in a context of defense responses against pathogen infection. By using deep sequencing, we identified a group of rice long small interfering RNAs (lsiRNAs) that are within the range of 25 to 40 nt in length. Our results show that some rice lsiRNAs are differentially expressed upon infection of Rhizoctonia solani, the causal agent of the rice sheath blight disease. Bioinformatic analysis and experimental validation indicate that some rice lsiRNAs can target defense-related genes. We further demonstrate that rice lsiRNAs are neither derived from RNA degradation nor originated as secondary small interfering RNAs (siRNAs). Moreover, lsiRNAs require OsDCL4 for biogenesis and OsAGO18 for function. Therefore, our study indicates that rice lsiRNAs are a unique class of endogenous sRNAs produced in rice, which may participate in response against pathogens.

Triggering efficient reconstructions of Co/Fe dual-metal incorporated Ni hydroxide by phosphate additives for electrochemical hydrogen and oxygen evolutions.

Alkaline electrochemical water splitting has been considered as an efficient way for the green hydrogen production in industry, where the electrocatalysts play the critical role for the electricity-to-fuel conversion efficiency. Phosphate salts are widely used as additives in the fabrication of electrocatalysts with improved activity, but their roles on the electrocatalytic performance have not been fully understood. Herein, we fabricate Co, Fe dual-metal incorporated Ni hydroxide on Ni foam using NaH2PO4 ((Co, Fe)NiOxHy-pi) and NaH2PO2 ((Co, Fe)NiOxHy-hp) as additive, respectively. We find that (Co, Fe)NiOxHy-hp with NaH2PO2 in the fabrication shows high activity and stability for both HER and OER (a overpotential of -0.629 V and 0.65 V at 400 mA cm-2 for HER and OER, respectively). Further experiment reveals that the reconstructed structures of electrocatalyst by using NaH2PO2 (hp) endow high electrocatalytic performances: (1) in-situ generated active metal improves the accumulation, transportation and activity of hydrogen species in the HER process; and (2) in-situ generated poor-crystalline hydroxide endows superior charge/mass transportation and kinetics improvements in the OER process. Our study may provide an insightful understanding on the catalytic performance of non-precious metal electrocatalysts by controlling additives and guidance for the design and synthesis of novel electrocatalysts.

Heteroatom Doping Promoted Ultrabright and Ultrastable Photoluminescence of Water-Soluble Au/Ag Nanoclusters for Visual and Efficient Drug Delivery to Cancer Cells.

Photoluminescence (PL) metal nanoclusters (NCs) have attracted extensive attention due to their excellent physicochemical properties, good biocompatibility, and broad application prospects. However, developing water-soluble PL metal NCs with a high quantum yield (QY) and high stability for visual drug delivery remains a great challenge. Herein, we have synthesized ultrabright l-Arg-ATT-Au/Ag NCs (Au/Ag NCs) with a PL QY as high as 73% and excellent photostability by heteroatom doping and surface rigidization in aqueous solution. The as-prepared Au/Ag NCs can maintain a high QY of over 61% in a wide pH range and various ionic environments as well as a respectable resistance to photobleaching. The results from structure characterization and steady-state and time-resolved spectroscopic analysis reveal that Ag doping into Au NCs not only effectively modifies the electronic structure and photostability but also significantly regulates the interfacial dynamics of the excited states and enhances the PL QY of Au/Ag NCs. Studies in vitro indicate Au/Ag NCs have a high loading capacity and pH-triggered release ability of doxorubicin (DOX) that can be visualized from the quenching and recovery of PL intensity and lifetime. Imaging-guided experiments in cancer cells show that DOX of Au/Ag NCs-DOX agents can be efficiently delivered and released in the nucleus with preferential accumulation in the nucleolus, facilitating deep insight into the drug action sites and pharmacological mechanisms. Moreover, the evaluation of anticancer activity in vivo reveals an outstanding suppression rate of 90.2% for mice tumors. These findings demonstrate Au/Ag NCs to be a superior platform for bioimaging and visual drug delivery in biomedical applications.

Sclerotinia sclerotiorum Protoplast Preparation and Transformation.

Sclerotinia sclerotiorum causes white mold, leading to substantial losses on a wide variety of hosts around the world. Many genes encoding effector proteins play important roles in the pathogenesis of S. sclerotiorum. Therefore, establishment of a transformation system for the exploration of gene function is necessarily significant. Here, we introduce a modified protocol to acquire protoplasts for transformation and generate knockout strains, which completements the transformation system of S. sclerotiorum.

Artificial nanovesicles for dsRNA delivery in spray induced gene silencing for crop protection.

Spray-Induced Gene Silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of dsRNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for dsRNA encapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP, and DODMA, and examined for their ability to protect and deliver dsRNA. All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome dsRNA instability in SIGS for crop protection.

Numerical study of hydrodynamic effects on Manila clam population distribution and transport in the Southwest Laizhou Bay, China.

Pelagic larvae of marine organisms are abundant on many continental shelves. Due to their importance as a biological resource and contribution to marine biodiversity, the dynamics of pelagic larvae have received wide attention. Numerical models are an efficient approach to assessing pelagic larval transport driven by various ocean dynamics. However, few studies have focused on the pelagic larval distribution of Manila clam populations and related dynamic factors in the southwestern Laizhou Bay (SLB) during late spring. A hydrodynamic model including realistic meteorologic and oceanic boundary conditions was coupled with a larval transport model to describe the pelagic larval distribution and transport processes. The hydrodynamic model was validated with observational and satellite-derived data. Effects of hydrodynamics and biological behavior on pelagic dynamics were further simulated with numerical experiments. During the early planktonic period, most clam larvae in the SLB were transported eastward or northeastward. Two potential larval settlement areas (LSAs) were recognized: the east side of the dike outside Guangli port and the Lao River estuary. The dominant controlling factor was southerly wind, and larvae's response to river plume or estuarine circulation played a secondary role. Larval transport depended on bottom subtidal currents when late-stage larvae settled near the bottom layer. The hydrodynamic and larval transport model established in this study can be applied to other bays and coastal waters. Understanding the clam larval distribution and transport dynamics in the SLB can provide a reference for predicting LSAs and biological resource management in coastal aquaculture areas.

Mutagenesis and structural studies reveal the basis for the specific binding of SARS-CoV-2 SL3 RNA element with human TIA1 protein.

Viral RNA-host protein interactions are indispensable during RNA virus transcription and replication, but their detailed structural and dynamical features remain largely elusive. Here, we characterize the binding interface for the SARS-CoV-2 stem-loop 3 (SL3) cis-acting element to human TIA1 protein with a combined theoretical and experimental approaches. The highly structured SARS-CoV-2 SL3 has a high binding affinity to TIA1 protein, in which the aromatic stacking, hydrogen bonds, and hydrophobic interactions collectively direct this specific binding. Further mutagenesis studies validate our proposed 3D binding model and reveal two SL3 variants have enhanced binding affinities to TIA1. And disruptions of the identified RNA-protein interactions with designed antisense oligonucleotides dramatically reduce SARS-CoV-2 infection in cells. Finally, TIA1 protein could interact with conserved SL3 RNA elements within other betacoronavirus lineages. These findings open an avenue to explore the viral RNA-host protein interactions and provide a pioneering structural basis for RNA-targeting antiviral drug design.

Multi-metal electrocatalyst with crystalline/amorphous structure for enhanced alkaline water/seawater hydrogen evolution.

The development of well-defined nanomaterials as non-noble metal electrocatalysts has broad application prospect for hydrogen generation technology. Recently, multi-metal electrocatalysts for hydrogen evolution reaction (HER) have attracted extensive attention due to their high catalytic performance arising from the synergistic effect of multi-metal interaction. However, most multi-metal catalysts suffer from the limited synergistic effect because of poor interfacial compatibility between different components. Here, a novel multi-metal catalyst (Ni/MoO2@CoFeOx) nanosheet with a crystalline/amorphous structure is demonstrated, which shows high HER activity. Ni/MoO2@CoFeOx exhibits an ultra-low overpotential of 18, 39, and 93 mV at 10 mA cm-2 in alkaline water, alkaline seawater and natural seawater, respectively, which outperformances most of the state-of-the-art non-noble metal compounds. In addition, the catalyst shows exceptional stability under 500 mA cm-2 in alkaline solution. In-situ Raman and other advanced structural characterization confirms the excellent catalytic activity is mainly contributed by: (1) the strong synergistic effect of multi-metal components provides multiple active sites in the catalytic process; (2) the crystalline/amorphous interface in Ni/MoO2@CoFeOx boosts the catalytically active sites and structure stability; (3) the crystalline phase enhances the intrinsic conductivity greatly; and (4) the amorphous phase provides abundant unsaturated sites for improved intrinsic catalytic activity. This work provides a feasible way to design electrocatalyst with high activity and stability for practical applications.

Facile formation of Zn-incorporated NiFe layered double hydroxide as highly-efficient oxygen evolution catalyst.

Electrochemical water splitting is the primary method to produce green hydrogen, which is considered an efficient alternative to fossil fuels for achieving carbon neutrality. For meeting the increasing market demand for green hydrogen, high-efficiency, low-cost, and large-scale electrocatalysts are crucial. In this study, we report a simple spontaneous corrosion and cyclic voltammetry (CV) activation method to fabricate Zn-incorporated NiFe layered double hydroxide (LDH) on commercial NiFe foam, which shows excellent oxygen evolution reaction (OER) performance. The electrocatalyst achieves an overpotential of 565 mV and outstanding stability of up to 112 h at 400 mA cm-2. The active layer for OER is shown to be ß-NiFeOOH according to the results of in-situ Raman. Our findings suggest that the NiFe foam treated by simple spontaneous corrosion has promising industrial applications as a highly efficient OER catalyst.

Facile and Stable CuInO2 Nanoparticles for Efficient Electrochemical CO2 Reduction.

Searching for electrocatalysts for the electrochemical CO2 reduction reaction (e-CO2RR) with high selectivity and stability remains a significant challenge. In this study, we design a Cu-CuInO2 composite with stable states of Cu0/Cu+ by electrochemically depositing indium onto CuCl-decorated Cu foil. The catalyst displays superior selectivity toward the CO product, with a maximal Faraday efficiency of 89% at -0.9 V vs the reversible hydrogen electrode, and maintains impressive stability up to 27 h with a retention rate of >76% in Faraday efficiency. Our systematical characterizations reveal that the catalyst's high performance is attributed to CuInO2 nanoparticles. First-principles calculations further confirm that CuInO2(012) is more conducive to CO generation than Cu(111) under applied potential and presents a higher energy barrier than Cu(111) for the hydrogen evolution reaction. These theoretical predictions are consistent with our experimental observations, suggesting that CuInO2 nanoparticles offer a facile catalyst with a high selectivity and stability for e-CO2RR.

RNA-binding proteins contribute to small RNA loading in plant extracellular vesicles.

Plants use extracellular vesicles (EVs) to transport small RNAs (sRNAs) into their fungal pathogens and silence fungal virulence-related genes through a phenomenon called 'cross-kingdom RNAi'. It remains unknown, however, how sRNAs are selectively loaded into EVs. Here, we identified several RNA-binding proteins in Arabidopsis, including Argonaute 1 (AGO1), RNA helicases (RHs) and annexins (ANNs), which are secreted by exosome-like EVs. AGO1, RH11 and RH37 selectively bind to EV-enriched sRNAs but not to non-EV-associated sRNAs, suggesting that they contribute to the selective loading of sRNAs into EVs. Conversely, ANN1 and ANN2 bind to sRNAs non-specifically. The ago1, rh11 rh37 and ann1 ann2 mutants showed reduced secretion of sRNAs in EVs, demonstrating that these RNA-binding proteins play an important role in sRNA loading and/or stabilization in EVs. Furthermore, rh11 rh37 and ann1 ann2 showed increased susceptibility to Botrytis cinerea, suggesting that RH11, RH37, ANN1 and ANN2 positively regulate plant immunity against B. cinerea.

Synthesizing Fluorescently Labeled dsRNAs and sRNAs to Visualize Fungal RNA Uptake.

Fungal pathogens are responsible for severe crop losses worldwide. Defending crops against fungal disease is critical for global food security; however, most current disease management approaches rely on chemical fungicides that can leave dangerous residues in the environment. RNA interference (RNAi) is an important process through which RNA molecules target and silence complementary genes, regulating gene expression during both transcription and translation. Recently, it has been discovered that some species of fungi can efficiently take up RNAs originating from their host plant and the environment. If these RNAs are complementary to fungal genes, this can lead to the targeting and silencing of fungal genes, termed "cross-kingdom RNAi," if the RNA originated from a plant host, or "environmental RNAi," if the RNA originated from the environment. These discoveries have inspired the development of spray-induced gene silencing (SIGS), an innovative crop protection strategy involving the foliar application of RNAs which target and silence fungal virulence genes for plant protection against fungal pathogens. The effectiveness of SIGS is largely dependent on the ability of fungi to take up environmental RNAs. Here, we describe the protocols used to label and visualize RNAs which are taken up by Botrytis cinerea. This protocol could easily be adapted for use across various fungal species. Determining the efficiency of RNA uptake by a specific fungal species is a critical first step to determining if SIGS approaches could be an effective control strategy for that fungus.

Expression of rice siR109944 in Arabidopsis affects plant immunity to multiple fungal pathogens.

Plant small RNA (sRNA)-mediated gene expression has a conserved role in regulating plant growth, development, and immunity. Heterologous expression of sRNA contributes to determining whether the function of sRNA is conservative or independent. We recently characterized the Tourist-miniature inverted-repeat transposable element (MITE)-derived siR109944 had a conserved function that enhanced susceptibility to Rhizoctonia solani infection by affecting auxin homeostasis in rice and Arabidopsis. To ascertain whether the function of rice siR109944 has a broad-spectrum immunity in Arabidopsis, we infected Arabidopsis with a variety of fungal pathogens. Overexpression of siR109944 in Arabidopsis increased susceptibility to Botrytis cinerea, Sclerotinia sclerotium, and Verticillium dahliae infection. Further studies found that Arabidopsis auxin-related miRNAs were suppressed in siR109944 OE. Our results demonstrated that overexpression of rice siR109944 in Arabidopsis affected immune responses to multiple pathogens by inhibiting auxin-related miRNA expression in planta.

The Biological Activity Research of the Nano-Drugs Based on 5-Fluorouracil-Modified Quantum Dots.

PURPOSE: Over the past decades, quantum dots (QDs) have shown the broad application in diverse fields, especially in intracellular probing and drug delivery, due to their high fluorescence intensity, long fluorescence lifetime, strong light-resistant bleaching ability, and strong light stability. Therefore, we explore a kind of therapeutic potential against cancer with fluorescent imaging. METHODS: In the current study, a new type of QDs (QDs@L-Cys-TAEA-5-FUA) capped with L-cysteine (L-Cys) and tris(2-aminoethyl)amine (TAEA) ligands, and conjugated with 5-fluorouracil-1-acetic acid (5-FUA) has been synthesized. Ligands were characterized by electrospray ionization mass spectrometry and H-nuclear magnetic resonance (1H NMR) spectroscopy. The modified QDs were characterized by transmission electron microscopy, ultraviolet and visible spectrophotometry (UV-Vis), and fluorescence microscopy. And the biological activity of modified QDs was explored by using MTT assay with HeLa, SMMC-7721 HepG2, and QSG-7701 cells. The fluorescence imaging of modified QDs was obtained by fluorescence microscope. RESULTS: The modified QDs are of controllable sizes in the range of 4-5 nm and they possess strong optical emission properties. UV-Vis and fluorescence spectra demonstrated that the L-Cys-TAEA-5-FUA was successfully incorporated into QD nanoparticles. The MTT results demonstrated that L-Cys-TAEA-5-FUA modified QDs could efficiently inhibit the proliferation of cancer cells as compared to the normal cells, illustrating their antitumor efficacy. The mechanistic studies revealed that the effective internalization of modified QDs inside cancer cells could inhibit their proliferation, through excessive production of intracellular reactive oxygen species, leading to apoptosis process. CONCLUSION: The present study suggests that modified QDs can enter cells efficiently and could be employed as therapeutic agents for the treatment of various types of cancers with fluorescent imaging.

A Lysosome-Targetable Fluorescence Probe Based on L-Cysteine-Polyamine-Morpholine-Modified Quantum Dots for Imaging in Living Cells.

PURPOSE: Quantum dots (QDs) are used as fluorescent probes due to their high fluorescence intensity, longevity of fluorescence, strong light-resistant bleaching ability and high light stability. Therefore, we explore a more precise probe that can target an organelle. METHODS: In the current study, a new class of fluorescence probes were developed using QDs capped with 4 different L-cysteine-polyamine-morpholine linked by mercapto groups. Ligands were characterised by Electrospray ionization mass spectrometry (ESI-MS), H-Nuclear Magnetic Resonance (1H NMR) spectroscopy, and 13C NMR spectroscopy. Modified QDs were characterized by Transmission Electron Microscope (TEM), Ultraviolet and visible spectrophotometry (UV-Vis), and fluorescence microscopy. And the biological activity of modified QDs was explored by using MTT assay with HeLa, SMMC-7721 and HepG2 cells. The fluorescence imaging of modified QDs was obtained by confocal laser scanning fluorescence microscopy (CLSM). RESULTS: Synthesized QDs ranged between 4 to 5 nm and had strong optical emission properties. UV-Vis and fluorescence spectra demonstrated that the cysteine-polyamine-morpholine were successfully incorporated into QD nanoparticles. The MTT results demonstrated that modified QDs had lesser cytotoxicity when compared to unmodified QDs. In addition, modified QDs had strong fluorescence intensity in HeLa cells and targeted lysosomes of HeLa cells. CONCLUSION: This study demonstrates the modified QDs efficiently entered cells and could be used as a potential lysosome-targeting fluorescent probe.

Manganese oxide at cadmium sulfide (MnOx@CdS) shells encapsulated with graphene: A spatially separated photocatalytic system towards superior hydrogen evolution.

Exploring novel, high-efficiency and durable catalysts is of vital importance to expedite current research on photocatalytic H2 evolution and address the energy and environmental issues. Herein, we rationally designed and synthesized a novel MnOx@CdS@GR photocatalyst with spatially separated dual co-catalysts for efficient visible-light-driven hydrogen production activity. In this spatially separated photocatalytic system, reduced graphene oxide (GR) and MnOx nanoparticles were anchored on the outer and inner surfaces of CdS shells acting as electron and hole collectors, respectively. The composition, microstructure and optical properties of the samples were thoroughly investigated. Photoluminescence spectra and photocurrent response as well as electrochemical impedance spectra were employed to reveal the separation and transfer ability of photo-generated charge carriers in the spatially separated MnOx@CdS@GR catalyst. Benefit from the synergistic effect including boosted light absorption capacity, enlarged specific surface area and increased separation and transfer efficiency of electron/hole pairs, the MnOx@CdS@GR exhibited superior H2 evolution performance, and the optimized H2-evolution rate reached a value of 5.45 mmol h-1 g-1, which is approximately 7.2 times than that of bare CdS. Moreover, this novel catalyst also displayed a long-term stability without apparent debasement in H2 evolution activity. Finally, the photocatalytic mechanism was proposed and discussed.

Boosted electrocatalytic activity of nitrogen-doped porous carbon triggered by oxygen functional groups.

The development of high-performance, low-price and durable doped carbon-based materials as multifunctional oxygen reduction reaction and oxygen evolution reaction catalysts is of great significance for the sustainable energy conversion devices. Adopting zinc zeolitic imidazolate framework and graphitic carbon nitride as nitrogen-sources and templates, we herein design a facile route to fabricate an oxygen (6.11%) functionalized and heavy nitrogen (23.54%) doped porous carbon (NOC-800) with high graphitization degree, high surface area and total pore volume. Electrochemical measurements indicate that as-obtained NOC-800 sample has satisfactory multifunctional oxygen-involving electrocatalytic properties in alkaline media, showing an onset and half-wave potential of -0.141 and -0.249 V vs. Ag/AgCl for oxygen reduction and an overpotential of 377 and 448 mV at 10 and 50 mA cm-2 for electrocatalytic oxygen evolution, respectively, even comparable to commercial RuO2 catalyst and majority of present mainstream metal-free catalysts. Moreover, the desirable stability of NOC-800 catalyst for both oxygen reduction and oxygen evolution reaction is also demonstrated. Combined with the analysis and discussion of the physicochemical characterization and electrochemical measurements, it is proposed and highlighted that oxygen functional groups introduced into nitrogen-doped carbon profitably contributes to high-efficiency overall oxygen-involving electrocatalytic activities.