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Schottky-contacted nanosensors have attracted extensive attention due to their high sensitivity and fast response time. In this article, we proved that the construction of Schottky contact by Pt nanoparticles (NPs) decoration can effectively improve the performance of V2O5 nanobelts photodetectors. After modified by Pt NPs, the photocurrent of V2O5 nanobelts is increased by more than two orders of magnitude, and the photoresponse speed is improved by at least three orders of magnitude. Detailed studies have shown that the performance enhancement is attributed to the formation of the Schottky contact at the electrode-semiconductor interface due to the decrease of surface gas adsorption and the increase of V2O5 work function after Pt NPs modification. The strong built-in field in the Schottky barrier region will quickly separate photogenerated carriers, thereby reducing the electron-hole recombination rate, resulting in the fast response time and an increase in the free carrier density. Moreover, it is found that this enhancement effect can be regulated by controlling the pressure to modulating the Schottky barrier height at the interface. Overall, the Pt NPs-modified V2O5 nanobelts photodetector exhibits a broad response spectrum (visible to near infrared), fast rise/fall response time (less than 6.12/6.15 ms), high responsivity (5.6 A/W), and high specific detectivity (6.9 × 108 Jones). This study demonstrates the feasibility of building a Schottky barrier to enhance the photodetection performance, which provides a general and effective strategy towards the construction and its practical application of supersensitive and fast-response nanosensors.

Based on the innovative strategy of EOR replacing OER, we originally proposed a “zinc–ethanol–air battery” achieving superior performance, which brought a new research direction for metal–air batteries.

Due to the rapid development of Anion-Exchange Membrane Fuel Cell (AEMFC), the development of non-noble metal electrocatalysts for hydrogen oxidation (HOR) in alkaline media has become urgent. Herein, the low-cost Mo–Co2P/CoP catalyst was synthesized, which can be used as a HOR electrocatalyst in alkaline medium. The improved performance is due to the surface modification of Mo species exposed to air oxidized, and the addition of Mo oxidized species accelerated the alkaline hydrogen electrode kinetics process. The development of active, inexpensive and stable HOR catalysts is of great significance for the commercialization of AEMFC.

Although lithium-sulfur batteries (LSBs) promise high theoretical energy density and potential cost effectiveness, their applications are severely impeded by the shuttling and sluggish redox kinetics of lithium polysulfides (LiPSs). In this context, a Co

Hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) have aroused great interest, but the high price of platinum group metals (PGMs) limits their development. The electronic reconstruction at the interface of a heterostructure is a promising strategy to enhance their catalytic performance. Here, MoO2/Ni heterostructure was synthesized to provide effective HER in an alkaline electrolyte and exhibit excellent HOR performance. Theoretical and experimental analyses prove that the electron density around the Ni atom is reduced. The electron density modulation optimizes the hydrogen adsorption and hydroxide adsorption free energy, which can effectively improve the activity of both HER and HOR. Accordingly, the prepared MoO2/Ni@NF catalyst reveals robust HER activity (η10 = 50.48 mV) and HOR activity (j0 = ∼1.21 mA cm-2). This work demonstrates an effective method to design heterostructure interfaces and tailor the surface electronic structure to improve HER/HOR performance.

Recently, the two-dimensional material Ti3C2Tx MXene has attracted interest from researchers in perovskite solar cells (PSCs) with its great advantages in terms of high transmittance, high conductivity, tunable work function, and solution processability. However, the MXene-based PSC performance has still been inferior to that of the traditional TiO2- or SnO2-based counterpart up until now. Some critical issues regarding to the MXene/perovskite interface still have not been well addressed. Herein, we used the Ti3C2Tx MXene as electron transport layer in PSCs via a room-temperature solution process followed by oxygen plasma treatment. Various characterization techniques were taken to establish the correlation between the surface properties and termination groups of MXene. We showed that oxygen plasma treatment could break parts of Ti-C bonds and generate abundant Ti-O bonds randomly distributed on MXene. The surface modification resulted in tunable work functions of MXene, as well as reduced trap states and improved electron transport close to the interface. In addition, the surface tension of MXene and corresponding perovskite morphology were thoroughly investigated by the contact angle and topography measurements. High-resolution XPS spectra indicated the Pb-O interactions between perovskite and MXene, which contributed to the device stability improvement.

Applying extensively excess ammonium halides in forming perovskites is a widely used approach to achieve high-performance perovskite light-emitting diodes (PeLEDs). However, most of these PeLEDs suffer from severe external quantum efficiency (EQE) roll-off at high current densities, thereby restricting the realization of high-brightness PeLEDs and laser diodes. In this work, we explore the underlying mechanism of the EQE roll-off in high-efficiency formamidinium lead iodide (FAPbI3)-based PeLEDs. By combining voltage-dependent electrical stress measurements and ex situ ion distribution analysis of PeLEDs, we found that the electric field-driven migration and local segregation of excess iodide ions, originated from nonstoichiometric precursors, trigger the EQE roll-off via promoting imbalanced charge injection. Based on this discovery, we introduced a simple wash-off treatment with chloroform to remove the excess iodides from the perovskite surface and demonstrated that the treatment is highly effective in suppressing the roll-off behavior. By combining the treatment and the use of an ultrathin poly(methyl methacrylate) (PMMA) interlayer, we achieved a high-brightness PeLED with an EQEmax of 19.6%, a critical current density of 1550 mA cm-2, and a radiancemax of 875 W sr-1 m-2. The study reveals the double-edge sword effect of precursor nonstoichiometry and highlights the importance of managing excess ions in perovskite films.

Aqueous zinc-ion batteries are regarded as one of the new promising rechargeable batteries. However, serious Zn dendrite growth causes short-circuit issues in the batteries. Herein, we report that arginine (Arg), a cationic surfactant electrolyte additive, can inhibit irregular and nonplanar dendrite growth and induce uniform Zn deposition. It shows a long cycle life (515 h) of Zn/Zn cells in the electrolyte containing Arg, which is ∼10 times longer than that of the electrolyte with no additive. The hydrolysis of Arg produces arginine cations (Arg⁺), which will be preferentially adsorbed on Zn dendrites due to the tip charge accumulation effect during the Zn plating process. Arg⁺ increases the overpotential for the nucleation of Zn dendrites and results in uniform Zn deposition. After about 350 cycles, the MnO₂/Zn cell shows 84.59% capacity retention and 99.85% average Coulomb efficiency in the electrolyte with the additive. The low-cost and nontoxic electrolyte additive identified in this work provides a new pathway toward inducing regular Zn deposition morphology.

3D mixed-halide perovskite-based red emitters combine excellent charge-transport characteristics with simple solution processing and good film formation; however, light-emitting diodes (LEDs) based on these emitters cannot yet outperform their nanocrystal counterparts. Here the use of diammonium halides in regulating the formation of mixed bromide–iodide perovskite films is explored. It is found that the diammonium cations preferentially bond to Pb–Br, rather than Pb–I, octahedra, promoting the formation of quasi-2D phases. It is proposed that the perovskite formation is initially dominated by the crystallization of the thermodynamically more favorable 3D phase, but, as the solution gets depleted from the regular A cations, thin shells of amorphous quasi-2D perovskites form. This leads to crystalline perovskite grains with efficiently passivated surfaces and reduced lattice strain. As a result, the diammonium-treated perovskite LEDs demonstrate a record luminance (10745 cd m−2) and half-lifetime among 3D perovskite-based red LEDs.

Metal halide perovskite light emitting diodes (PeLEDs) have recently experienced rapid development due to the tunable emission wavelengths, narrow emission linewidth and low material cost. To achieve state-of-the-art performance, the high photoluminescence quantum yield (PLQY) of the active emission layer, the balanced charge injection, and the optimized optical extraction should be considered simultaneously. Multiple chemical passivation strategies have been provided as controllable and efficient methods to improve the PLQY of the perovskite layer. However, high luminance under large injection current and high external quantum efficiency (EQE) can hardly be achieved due to Auger recombination at high carrier density. Here, we decreased the electron injection barrier by tuning the Fermi-level of the perovskite, leading to a reduced turn on voltage. Through molecular doping of the hole injection material, a more balanced hole injection was achieved. At last, a device with modified charge injection realizes high luminance and quantum efficiency simultaneously. The best device exhibits luminance of 55,000 cd m−2, EQE of 8.02% at the working voltage of 2.65 V, current density of 115 mA cm−2, and shows EQE T50 stability around 160 min at 100 mA cm−2 injection current density.

Due to the rapid development of alkaline polymer electrolyte fuel cells and water splitting, it is becoming increasingly urgent to develop non-precious metal electrocatalysts for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) in alkaline medium. Herein, Co2P/CoP hybrid is synthesized from cobalt carbonate hydroxide (CoCH) precursor, and further evaluated for the electrocatalytic HOR and HER in alkaline electrolytes. Specifically, benefiting from the reasonable hybrid structure that integrate suitable hydrogen adsorption energy of CoP and excellent conductivity of Co2P, Co2P/CoP hybrid exhibits excellent catalytic activities. The Co2P/CoP@NF hybrid has impressive HER activity, with a current density of −10 mA cm−2 at the overpotentials of −61 mV and the Tafel slope of 55.1 mV dec−1, which can compete with recently reported transition metal phosphides and cobalt-based catalysts. In addition, the exchange current density of Co2P/CoP@NF hybrid is ~ 0.82 mA cm−2 for HOR, which is close to commercial Pt/C catalyst (~1.14 mA cm−2).

Metal oxyhydroxides are regarded as active catalysts for oxygen evolution reaction (OER). Herein, we creatively report NiFeOOH is greatly activated by N-doping to get an efficient OER catalyst. The effect of N-doping in the resulted metal oxyhydroxides for the OER is revealed for the first time. N-doped NiFeOOH (N-NiFeOOH) is in-situ derived from N-(NiFe)3S2 precatalyst by electrochemical oxidation. N-NiFeOOH exhibits superior performance with a low overpotential of 278 mV at the current density of 100 mA cm−2 and a small Tafel slope of 35.3 mV dec−1, which is comparable to the most excellent non-noble catalysts. DFT calculations reveal that N-doping would lower the d-band center of the surface metal atoms and in turn increase the adsorption ability of *OH on NiFeOOH, thereby reducing the OER overpotential. The key role of N-doping in the NiFeOOH for enhancing OER performance is reported for the first time, which will shed light on the design of catalysts.

Development of non-noble metal electrocatalysts for hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in acid is a great challenge for the development of polymer electrolyte m...

This study reports a high-performing nonprecious metal catalyst for the oxygen reduction reaction that is composed of highly dispersed Fe centered active sites on bamboolike carbon nanotubes. NH2-MIL-88B is used as the iron source and ZIF-8 as the carbon source. The precursors are uniformly mixed by ball milling, which destroys their crystal structures. A bamboolike carbon nanotube network results from the pyrolysis of the mixed precursors. The morphology is controlled by the proportion of the precursors and the pyrolysis temperature. The catalyst shows excellent oxygen reduction activity in both half-cell and full-cell tests. The onset potential and half-wave potential are 0.96 and 0.78 V vs RHE, respectively. In the fuel cell test, the current density reaches 0.85 A cm-2 at 0.7 V and 1.24 A cm-2 at 0.6 V (iR-corrected). The novel synthesis approach of the highly dispersed catalyst provides new strategy in the design of high effective nonprecious metal catalysts for fuel cell.

This work reveals a balance between the improved oxygen reduction reaction/oxygen evolution reaction activity of nitrogen doped carbon and the concomitant activity in the decomposition of the electrolyte of the Lithium-oxygen battery. The capacity and cyclability of Lithium-oxygen battery increase with the nitrogen content to a vertex, then decrease with higher nitrogen content. The largest capacity of 7250 mA g−1 and the best long-term stability of 71 cycles over 420 h are found in a catalyst with proper content of nitrogen. It is also found nitrogen doping can improve the work function of the carbon material, making it more resistant to decomposition in the working conditions of Lithium-oxygen battery.

The development of hydrogen energy is limited by the high cost of platinum group metals (PGM). There is an urgent need to design efficient PGM-free electrocatalysts in the hydrogen electrode. Herein, Janus Ni/W bimetallic materials are proposed as an effective PGM-free bifunctional hydrogen electrocatalyst. By constructing the bimetallic materials, a synergistic effect is realized to enhance the reaction kinetics and improve the catalytic performance. In general, Ni can provide excellent H

For the development of high-performance zinc–air batteries, it is necessary to increase the kinetics of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) as much as possible. In this work, different coordination structures of Co loaded on concave hollow carbon octadecahedron (CNQD/CoNBs) were prepared by adding g-C3N4 into the synthesis process of Co-based zeolitic imidazolate framework and adjusting the stress balance of the framework structure in the pyrolysis process. This method can greatly increase the specific surface area and the number of micropores of the material for exposing more active sites to accelerate the reaction kinetics. The prepared catalyst shows excellent bi-functional performance for OER and ORR, and it is applied in efficient rechargeable zinc–air battery to achieve high discharge power density of 210 mW/cm2 and favorable stability over long charge/discharge cycles. This research provides an effective strategy to design high-efficiency bi-functional electrocatalysts.

Two-dimensional (2D) transition metal carbides (MXene) have shown great advantages as electrode materials in the new generation of energy storage, especially in supercapacitors. However, the inherent low specific capacitance and restacking layers of nanosheets that occur during electrode preparation further reduce the electrochemical performance of the materials. Based on this, we design a N, S co-doping electrode with a three-dimensional (3D) structure, which not only improves the specific capacitance through fundamentally modifying the electronic structure of the electrode materials, but also effectively improves the rate performance of the electrode by preventing the restacking of 2D materials. The N, S co-doping 3D architecture Ti

The oxygen evolution reaction (OER) is crucial for hydrogen production from water splitting and rechargeable metal-air batteries. However, the four-electron mechanism results in slow reaction kinetics, which needed to be accelerated by efficient catalysts. Herein, a hybrid catalyst of novel nickel-iron layered double hydroxide (NiFe LDH) on porous indium tin oxide (ITO) is presented to lower the overpotential of the OER. The as-prepared NiFe LDH@ITO catalyst showed superior catalytic activity toward the OER with an overpotential of only 240 mV at a current density of 10 mA/cm2. The catalyst also offered high stability with almost no activity decay after more than 200 h of chronopotentiometry test. Furthermore, the applications of NiFe LDH@ITO in (flexible) rechargeable zinc-air batteries exhibited a better performance than commercial RuO2 and can remain stable in cycling tests. It is supposed that the superior catalytic behavior originates from the ITO conductive framework, which prevents the agglomeration and facilitates the electron transfer during the OER process.

The earth-abundant iron and nitrogen doped carbon (Fe-N-C) catalyst has great potential to substitute noble metal catalysts for oxygen reduction reaction (ORR) in H2-O2 proton exchange membrane fuel cells (PEMFCs). Herein, we report the preparation of Fe-N4 moiety doped carbon nanotubes (CNTs) by ball milling and two-step pyrolysis with dual metal-organic frameworks (MOFs) as the precursor. This catalyst shows high ORR catalytic performance and stability. Different from traditional inorganic iron sources, the MOF structure can effectively prevent the iron metal from aggregating during pyrolysis. In PEMFC, the catalyst shows high current density (0.39 A/cm2 at 0.7 V) and power density (850 mW/cm2). Such a method brings inspiration for the reasonable design of FeNC catalysts with high catalytic activity for H2-O2 PEMFCs.

This work reports a rational design of non-precious metal catalyst for oxygen reduction reaction in acidic media to be used in polymer electrolyte membrane fuel cell. A strategy is designed to avoid the agglomeration of metal compound during the pyrolysis of precursor. MgO template is introduced into a 1-10-phenanthroline-iron (II) precursor to promote the evolution of Fe-Nx active sites while avoiding the formation of inactive species. The template also contributes to the formation of micro/mesoporous structure. The as-prepared catalyst shows good performance in half-cell test with half-wave potential of 0.80 V in acidic media. The catalyst reaches a current density of 0.76 A cm −2 at 0.6 V iR-free along with encouraging durability in H 2 –O 2 fuel cell test.

The device stability and toxic-solvent-free processing are indispensable development to industrialize organometal halide perovskite solar cells. In this work, the conventional top surface of vapor prepared 3D-MAPbI3 was replaced by 2D-(BA)2(MA)n‐1PbnI3n+1 perovskite platelet via molecular substitution from MA (CH3NH) to BA (C4H9NH2). Our fully vapor process fabricated a 3D-2D perovskite heterojunction for solar cell application, realizing the power conversion efficiency as high as 16.50% and the average one as 15.40%. Furthermore, unencapsulated devices can sustain their 81% efficiency after 30 days under 55% RH, and also 74% efficiency after 30 days under 80 °C heat stress. Stability of humidity resistance arises from the reduced n value of 2D perovskite caused by the surface reaction of moisture, and the improvement of thermal stability comes from the buffering of MA molecules release. Meanwhile, the fabrication of large scale device with high efficiency is also demonstrated in our experiment.

Ruddlesden–Popper perovskites (RPPs) have attracted intense attention owing to their superior stability. However, the interspace and weak interaction between the inorganic layers inhibits direct ch...

Hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) have aroused great interest, but the high price of platinum group metals (PGMs) limits their development. The electronic reconstruction at the interface of a heterostructure is a promising strategy to enhance their catalytic performance. Here, MoO

Schottky-contacted nanosensors have attracted extensive attention due to their high sensitivity and fast response time. In this article, we proved that the construction of Schottky contact by Pt nanoparticles (NPs) decoration can effectively improve the performance of V

Recently, the two-dimensional material Ti

Significance Advanced oxidation processes (AOPs) are widely applied to the treatment of refractory organic pollutants in the environment. However, the continuous addition of oxidant limits their application for in situ remediation of river courses. Hydrogen peroxide (H 2 O 2 ) is the most commonly used oxidant in AOPs. Photosynthesis of H 2 O 2 is a promising approach to provide oxidants for AOPs in an in situ and continuous way. However, limited by the rapid charge recombination, organic electron donors and O 2 atmosphere are usually required. Here, a Z-scheme heterojunction photocatalyst achieved the production of H 2 O 2 in pure water and open air. The regulation and potential mechanism of the Z-scheme and type II heterojunctions are revealed. This study demonstrates a feasible strategy for developing efficient Z-scheme photocatalysts.

Long-term stability of organic-inorganic hybrid perovskite solar cells (PSCs) is inhibited by ion diffusion. Herein, we introduce a thermally stable and hydrophobic silicone resin layer with a network structure as an interfacial layer between the perovskite and the hole-transporting layer (HTL). Experimental and theoretical investigations confirm that the small Si-O-Si unit in the network forms both Si-I and Pb-O bonds with the perovskite surface, which physically and chemically inhibit the diffusion and self-release of iodine. Besides, the silicone resin layer suppresses the thermal crystallization of spiro-OMeTAD and optimizes the interfacial energy level alignment for hole extraction. The power conversion efficiency (PCE) of a perovskite solar cell with a silicone resin layer is improved to 21.11%. The device maintains more than 90.1% of its original PCE after 1200 h under 85 °C thermal stress, 99.6% after 2000 h under RH ∼55 ± 5%, and 83% of its original PCE after light soaking in air for 1037 h.

Perovskite light emitting diodes suffer from poor operational stability, exhibiting a rapid decay of external quantum efficiency within minutes to hours after turn-on. To address this issue, we explore surface treatment of perovskite films with phenylalkylammonium iodide molecules of varying alkyl chain lengths. Combining experimental characterization and theoretical modelling, we show that these molecules stabilize the perovskite through suppression of iodide ion migration. The stabilization effect is enhanced with increasing chain length due to the stronger binding of the molecules with the perovskite surface, as well as the increased steric hindrance to reconfiguration for accommodating ion migration. The passivation also reduces the surface defects, resulting in a high radiance and delayed roll-off of external quantum efficiency. Using the optimized passivation molecule, phenylpropylammonium iodide, we achieve devices with an efficiency of 17.5%, a radiance of 1282.8 W sr−1 m−2 and a record T50 half-lifetime of 130 h under 100 mA cm−2., Perovskite light emitting diodes suffer from operational stability, showing rapid decay of performance within minutes to hours after turn-on. Here, the authors investigate how the steric and Coulomb interaction of ammonium passivation molecules with varying alkyl chain length can improve device stability by suppressing iodide ion migration.

The electroluminescence efficiency of perovskite light-emitting diodes (PeLEDs) has gained notable achievements, but the poor stability under electric stress severely impedes future practical use. Here, an alkyldiammonium 1,4-butanediamine (BDA) is incorporated into perovskite emitting layer, which substantially optimizes electrochemical stability and minimizes interfacial deep traps under large external bias. The BDA-PeLED shows a record operational half-lifetime T50 of 189.4 h at a high current density of 100 mA cm−2 and 589 hours under 50 mA cm−2. Additionally, the device maintains its original performance upon 2500 cycles of voltage scan and withstands 10000 times of ON-OFF under a pulsed voltage of 2.5 V. Further degradation mechanism study reveals that the main origins of the instability property of PeLEDs without BDA are the generation of deep traps at the interfaces and the infiltration of anions into adjacent layers. The significantly enhanced electrochemical stability suggests that alkyldiammonium cation incorporation provides a direction to solve the instability issue.

The poor stability of perovskite light-emitting diodes (PeLEDs) is a key bottleneck that hinders commercialization of this technology. Here, the degradation process of formamidinium lead iodide (FAPbI3)-based PeLEDs is carefully investigated and the device stability is improved through binary-alkalication incorporation. Using time-of-flight secondary-ion mass spectrometry, it is found that the degradation of FAPbI3-based PeLEDs during operation is directly associated with ion migration, and incorporation of binary alkali cations, i.e., Cs+ and Rb+, in FAPbI3 can suppress ion migration and significantly enhance the lifetime of PeLEDs. Combining experimental and theoretical approaches, it is further revealed that Cs+ and Rb+ ions stabilize the perovskite films by locating at different lattice positions, with Cs+ ions present relatively uniformly throughout the bulk perovskite, while Rb+ ions are found preferentially on the surface and grain boundaries. Further chemical bonding analysis shows that both Cs+ and Rb+ ions raise the net atomic charge of the surrounding I anions, leading to stronger Coulomb interactions between the cations and the inorganic framework. As a result, the Cs+–Rb+-incorporated PeLEDs exhibit an external quantum efficiency of 15.84%, the highest among alkali cation-incorporated FAPbI3 devices. More importantly, the PeLEDs show significantly enhanced operation stability, achieving a half-lifetime over 3600 min.

At present, perovskite solar cells have achieved a conversion efficiency that can be comparable to conventional silicon solar cells, but the stability of perovskite is still difficult to make great breakthroughs. And the mechanism of the intrinsic instability and the instability caused by the external environment of the perovskite are not yet clear. Although XPS (X-ray photoelectron spectroscopy) and UPS (ultraviolet photoelectron spectroscopy) are two widely used methods in perovskite investigation, the instability phenomenon of perovskite film during the XPS and UPS measurement has not been taken seriously. This work aims to illustrate the effects of thermal annealing and illumination of ultraviolet light and X-rays on the composition and energy level structure of perovskite films. It was found that the composition and the work function of perovskite film are highly sensitive to annealing temperature while the valence band maximum (VBM) remains basically unchanged. And the perovskite CH3NH3PbI3 film tends to degrade into different products under X-ray and ultraviolet light. The intrinsic degradation process in vacuum is: the CH3NH3I molecules leave surface with increasing temperature.

Summary The expensive and unstable organic hole transport layer (HTL) is one of the crucial problems that hampers the wide application of perovskite solar cells. Here, an MAPbI3-(BA)2(MA)n−1PbnI3n+1 3D-2D perovskite-perovskite planar heterojunction (PPPH) through a facile BAI and MAPbI3 interfacial ion exchange process was conducted. A graded band structure was formed for efficient charge separation, and the conductivity of the 2D perovskite can be tuned by extrinsic FA incorporation, which provides effective conducting channels for holes, making the modified 2D perovskite layer a promising and stable HTL. Optimized solar cells based on 3D-2D PPPH showed a champion power conversion efficiency (PCE) of 13.15% initially and 16.13% after thermal aging, and could maintain 71% output for 50 days under 65% humidity, and 74% for 30 days under 85°C, without encapsulation. This work points to realize low cost and ambient compatible PPPH solar cells with high PCE and robust stability.

H2-O2 proton exchange membrane fuel cells (PEMFCs), one of the applications of hydrogen energy with specific energy density of 143 MJ/kg, might be a promising alternative to replace the use of fossil energy. The key to accelerate the application of PEMFCs is to design an efficient non-precious metal catalyst to lower the overpotential of the cathode oxygen reduction reaction (ORR). Herein, we developed a novel iron and nitrogen doped carbon (FeNC) catalyst using ferrocene as iron source, ZIF-8 as organic framework as well as the main carbon source. The regular morphology of ZIF-8 and ferrocene can prevent active sites from agglomeration, resulting a homogenous distribution of Fe, N and C. Moreover, the high specific area, porous structure and abundant catalytic Fe and N species gave rise to the ORR performance of the catalyst. As a result, the as-prepared FeNC catalyst showed an onset and half-wave potential of 0.95 V and 0.78 V in 0.1 M HClO4 with 1600 rpm, respectively. The catalysts were also applied in a PEMFC as the cathode catalysts with an open circuit voltage of more than 0.9 V and a maximum power density of 601 mW/cm2. Additionally, the as-prepared FeNC-1:30 catalyst showed a current density of 380 mA/cm2 at 0.7 V, which outperformed other as-prepared catalysts.

In this work, we report our recent efforts in developing carbon nanotube cross-linking MOF-derived Fe/N/C catalysts as oxygen reduction electrocatalysts for fuel cell. It is witnessed that the carbon nanotube cross-linking strategy can effectively improve the activity and stability of fuel cell, which can be assigned to its fast and convenient electron conduction channels offered by loosely cross-linked carbon nanotubes. The results of 57Fe Mossbauer spectroscopy show that there are three spin states of Fe-N4 structure in the material, of which low-spin state D1-FeIIN4 and high-spin state D3-N-FeN4 are both considered to be the main active sites of oxygen reduction reaction. For fuel cell, high performance of 0.732 A cm−2 at 0.7 V is reached. The novel cross-linking catalyst sheds light on the development of non-precious metal catalysts for fuel cells.

A non-noble metal Fe/N/C catalyst is prepared by pyrolyzing the ball-milled mixture of graphitized carbon ribbon, iron precursor, and nitrogen precursor in ammonia. The Fe/N/C catalyst shows high ORR activity in alkaline solution, together with much improved stability compared with Pt/C catalyst. In the catalyst, FeN particles are covered by graphitic carbon layers. The activity is proposed to originate from the FeN and Fe/N/C sites. The stability is explained by the protecting effect of the carbon layers surrounding the FeN particles. The ORR mechanism on the Fe/N/C catalyst is proposed to be similar with Pt/C catalyst based on the Tafel plots. The Fe/N/C catalyst shows great potential in ORR in alkaline solution, while the performance in acid still needs improvement.

This work designed a facile preparation for an SiO2/C composite as the anode material for lithium ion battery. Both SiO2 and carbon are amorphous. SiO2 and carbon are mixed uniformly. The SiO2/C composite shows high specific capacity, cycle stability, and rate capability in lithium ion battery charge–discharge test. A stable reversible capacity of 1024 mA h/g at the current density of 100 mA/g is reached. The capacity retains 83% after 100 cycles. The uniform mixture of SiO2 and carbon leads to reduced volume change during the lithiation and delithiation of SiO2, together with the amorphous nature of SiO2 explains the high cycling stability. The carbon coating is a key factor for the high capacity and stability due to the increased electrical conductivity and reduced volume change. The resistance of the solid electrolyte interface film and charge transfer resistance of the SiO2/C composite are much smaller than those of pure carbon, which is a direct proof of the improved conductivity of the material by the carbon coating.

Cathode interlayers (CILs) with low-cost, low-toxicity, and excellent cathode modification ability are necessary for the large-scale industrialization of polymer solar cells (PSCs). In this contribution, we demonstrated one-pot synthesized carbon quantum dots (C-dots) with high production to serve as efficient CIL for inverted PSCs. The C-dots were synthesized by a facile, economical microwave pyrolysis in a household microwave oven within 7 min. Ultraviolet photoelectron spectroscopy (UPS) studies showed that the C-dots possessed the ability to form a dipole at the interface, resulting in the decrease of the work function (WF) of cathode. External quantum efficiency (EQE) measurements and 2D excitation-emission topographical maps revealed that the C-dots down-shifted the high energy near-ultraviolet light to low energy visible light to generate more photocurrent. Remarkably improvement of power conversion efficiency (PCE) was attained by incorporation of C-dots as CIL. The PCE was boosted up from 4.14% to 8.13% with C-dots as CIL, which is one of the best efficiency for i-PSCs used carbon based materials as interlayers. These results demonstrated that C-dots can be a potential candidate for future low cost and large area PSCs producing.