Hollow cobalt oxide nanoparticles embedded in nitrogen-doped carbon nanosheets as an efficient bifunctional catalyst for Zn–air battery

Rational design of low-cost, highly electrocatalytic activity, and stable bifunctional electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) has been a great significant for metal–air batteries. Herein, an efficient bifunctional electrocatalyst based on hollow cobalt oxide nanoparticles embedded in nitrogen-doped carbon nanosheets(Co/N-Pg) is fabricated for Zn–air batteries. A lowcost biomass peach gum, consisting of carbon, oxygen, and hydrogen without other heteroatoms, was used as carbon source to form carbon matrix hosting hollow cobalt oxide nanoparticles. Meanwhile, the melamine was applied as nitrogen source and template precursor, which can convert to carbon-based template graphitic carbon nitride by polycondensation process. Owing to the unique structure and synergistic effect between hollow cobalt oxide nanoparticles and Co-N-C species, the proposal Co/N-Pg catalyst displays not only prominent bifunctional electrocatalytic activities for ORR and OER, but also excellent durability. Remarkably, the assembled Zn–air battery with Co/N-Pg air electrode exhibited a low discharge-charge voltage gap(0.81 V at 50 mA cm^-2) and high peak power density(119 mW cm^-2) with long-term cycling stability. This work presents an effective approach for engineering transition metal oxides and nitrogen modified carbon nanosheets to boost the performance of bifunctional electrocatalysts for Zn–air battery.

Interface Engineering of CoS/CoO@N‑Doped Graphene Nanocomposite for High‑Performance Rechargeable Zn–Air Batteries

Low cost and green fabrication of high-performance electrocatalysts with earth-abundant resources for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are crucial for the large-scale application of rechargeable Zn-air batteries(ZABs).In this work,our density functional theory calculations on the electrocatalyst suggest that the rational construction of interfacial structure can induce local charge redistribution,improve the electronic conductivity and enhance the catalyst stability.In order to realize such a structure,we spatially immobilize heterogeneous CoS/CoO nanocrystals onto N-doped graphene to synthesize a bifunctional electrocatalyst(CoS/CoO@NGNs).The optimization of the composition,interfacial structure and conductivity of the electrocatalyst is conducted to achieve bifunctional catalytic activity and deliver outstanding efficiency and stability for both ORR and OER.The aqueous ZAB with the as-prepared CoS/CoO@NGNs cathode displays a high maximum power density of 137.8 mW cm^−2,a specific capacity of 723.9 mAh g^−1 and excellent cycling stability(continuous operating for 100 h)with a high round-trip efficiency.In addition,the assembled quasi-solid-state ZAB also exhibits outstanding mechanical flexibility besides high battery performances,showing great potential for applications in flexible and wearable electronic devices.

Correction to:Interface Engineering of CoS/CoO@N-Doped Graphene Nanocomposite for High-Performance Rechargeable Zn-Air Batteries

In the original publication,the label text“Pt/C”in Fig.5 should be“Pt/C+IrO_(2)”.In Fig.5d,the X-axis label“Poten-tial(V vs.RHE)”should be replaced with“Specific capacity(mAh g^(−1))”.In Fig.5e,the Y-axis label“Potential(V vs.RHE)”should be replaced with“Voltage(V)”.In Fig.5g,the X-axis label“Time(h)”should be replaced with“Cycle number(n)”.The Y-axis label“ΔE(V vs.RHE)”should be replaced with“Voltage(V)”.The number“1.4”and“1.6”should be replaced with 1.6 and 2.0,respectively.The cor-responding data analysis and conclusions in the manuscript are not affected and thus not to be changed.The correct Fig.5 is provided in this correction.

Cryo-induced closely bonded heterostructure for effective CO2 conversion:The case of ultrathin BP nanosheets/g-C3N4

Black phosphorus(BP),an interesting and multi-functional non-metal material,has attracted widespread attention.In this work,2D BP/2D g-C3N4 heterostructure had been fabricated at extremely low temperature,which was used to reduce CO2 for the first time.With introduction of 2D BP,the separation of photogenerated holes and electrons was extremely boosted,and composites showed excellent photocatalytic performance(CO2 to CO).Meanwhile,the targeted composite could keep high selectivity for CO generation and CO generation rate can be up to 187.7μmol g−1 h^−1.The formation process of the unique heterostructure and the key factor affecting the photocatalytic performance were also discussed.This work provides a new approach for designing metal free photocatalyst,which is used for CO2 reduction.

Engineering Electronic Density and Coordination Environment of Mn–Nx Sites via Zn Cooperation for Quasi-Solid-State Zinc-Air Batteries

Due to the poor Fenton reactivity,single-atom Mn-based materials are generally identified as one of the most promising active catalysts for oxygen reduction reaction(ORR).Regulating the electronic density and coordination environment of atomically dispersed Mn centers is an effective strategy to enhance ORR activity of Mn-based materials.By introducing Zn sites,atomically dispersed Mn centers with multitudes of coordination(including Zn/Mn–Nx and Mn–Nx moieties)can be constructed to form Mn-based ORR catalyst(Zn/Mn-NC)with dual-atom sites.Around Mn–Nx sites,the Zn atoms can effectively modulate the electronic structure and coordination state of Mn centers in Zn/Mn-NC through d–d orbital coupling.The electronic interaction between Zn and Mn sites improves ORR activity,thereby optimizing the oxygen adsorption energy of Mn sites in Zn/Mn-NC and reducing the overall energy barrier.Zn/Mn-NC displays higher ORR half-wave potential than Pt/C(0.89 V vs 0.86 V).The quasi-solid-state zinc-air battery(ZAB)with Zn/Mn-NC as the cathode displayed excellent rechargeability,recyclability,and mechanical robustness.The strategy presented regulates the electronic density and coordination environment of singleatom Mn-based ORR catalysts in quasi-solid-state ZABs.

具有NIR-Ⅱ吸收的碳包覆磁铁矿纳米团簇用于成像引导的光热-化学动力学协同治疗

化学动力学疗法(CDT)是基于磁铁矿纳米酶治疗癌症的新兴治疗方式.但是,它的低催化能力和单模治疗限制了其治疗功效.本工作中,我们开发了一种在第二近红外(NIR-Ⅱ)窗口中具有高吸光度的碳涂覆的磁铁矿纳米团簇(CCMNCs),用于NIR-Ⅱ光热增强的化学动力抗癌疗法.这种尺寸约58 nm的CCMNCs通过使用二茂铁作为单一前体的一步溶剂热法合成.CCMNCs不仅用作肿瘤靶向磁共振成像的造影剂,而且还吸收并将NIR-Ⅱ辐射转化为局部热量,用于高温杀死癌细胞.CCMNCs在酸溶液中产生的亚铁离子和铁离子催化Fenton反应生成CDT的羟基自由基(·OH),并减少作为自由基清除剂的细胞内谷胱甘肽.本文报道的CCMNCs通过组合的化学动力学光热处理的协同效应显示出优异的治疗功效.

Fabrication of highly efficient heterostructured Ag-CeO2/g-C3N4 hybrid photocatalyst with enhanced visible-light photocatalytic activity

On the basis of hydrothermal synthesis of Ag-CeO2 microspheres,Ag-CeO2/g-C3N4 composite photocatalyst with heterostructure was prepared by simple solvent evaporation of Ag-CeO2 and g-C3N4.To characterize the composition,structure,morphology and light absorption properties of the as-prepared Ag-CeO2/g-C3N4 composites,XRD,FTIR XPS,SEM,TEM,PL,BET and UV-vis DRS were used,respectively.The as-prepared photocatalyst was subjected to photocatalytic degradation of pollutants,and the prepared composite material has excellent photocatalytic activity for photodegradation of methylene blue(MB).The research shows that the photocatalytic properties of Ag-CeO2/g-C3N4 composites were related to the mass ratio of Ag-CeO2 microspheres and g-C3N4 nanosheets.When the ratio of Ag-CeO2 microspheres:g-C3N4 is 1:5,the composites have the highest photocatalytic activity,which was 9.6 and 3.3 times that of single Ag-CeO2 and g-C3N4,respectively.The improvement of photocatalytic activity is attributed to the heterostructure between the composite materials and the addition of noble metal silver,and the degradation of methylene blue by the visible light irradiation material is greatly improved.Finally,an attempt was made to analyze the principle of photocatalytic degradation of pollutants in prepared materials.

Biotemplated fabrication of hierarchical mesoporous CeO_2 derived from diatom and its application for catalytic oxidation of CO

Hierarchically hollow nanostructures have been the focus of numerous studies due to their prominent physicochemical properties that differ significantly from bulk materials and their potential for extensive applications. We present a novel diatom-based scaffold for the synthesis of hierarchically biomorphic CeO2 with special porous structure via incorporating Ce ions into the frustule.Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption measurements were adopted to characterize the products. Owing to its unique hierarchical structure and periodic meso-macro scale features, the obtained CeO2 exhibits high catalytic activity in CO oxidation. This facile strategy may design a new way towards replicating desired biological structures for metal oxide catalyst in other potential applications.

Facile fabrication of CeF_(3)/g-C_(3)N_(4) heterojunction photocatalysts with upconversion properties for enhanced photocatalytic desulfurization performance

Cerium fluoride(CeF_(3))semiconductor with upconversion property was constructed on graphite carbonitride(g-C_(3) N_(4))nanosheets by microwave hydrothermal method.The X-ray diffraction,transmission election microscopy,Fourier transform infrared,and X-ray photoelectron spectra techniques were used to characterize the CeF_(3)/g-C_(3)N_(4) nanocomposite.The study shows that CeF_(3) has upconversion property and can convert visible light(Vis)and near-infrared light(NIR)into ultraviolet light(UV).Mo reover,CeF3 and g-C_(3) N_(4) can form well-defined heterojunction and promote the effective separation of photogenerated electrons and holes.The synergistic effect of the CeF_(3)/g-C_(3)N_(4) nanocomposite was evaluated by photocatalytic degradation of dibenzothiophene(DBT).The optimum photocatalyst of CeF_(3)/g-C_(3)N_(4)(40 wt%)composites exhibit the highest photocatalytic desulfurization rate of the model oil under visible light radiation.