To improve the layer spacing and the electrocatalytic performance of Ti₃C₂, the carbon nanotubes (CNTs) was utilized to tailor the microstructure. Layered Ti₃C₂, obtained by etching Ti₃AlC₂ with HF, hydroxylated carbon nanotubes (CNTs) and potassium tetrachloropalladate (K₂PdCl₄) were used to synthesize Pd naoparticles supported on Ti₃C₂-CNT (Pd/Ti₃C₂-CNT) catalyst through ultrasonic dispersion and solvothermal method. XRD, FE-SEM and XPS were adopted to investigate the effect of CNT on the microstructural tailoring of Ti₃C₂ interlayers. The electrocatalytic performance of Pd/ Ti₃C₂-CNT catalysts for both formic acid and methanol in acidic and alkaline solutions, were investigated by cyclic voltammetry, chronoamperometry, and AC impedance spectroscopy, respectively. The results validated that the intercalation of CNTs into Ti₃C₂ interlayers, whose “bridge” effects benefit the electron transportation in the catalysts, and thus the electrocatalytic performance of Pd/Ti₃C₂-CNT was elevated.

Tungsten carbide nanoparticle-encased graphite-like mesoporous carbon (WC/MG), as a precious metal- free cathode catalyst for oxygen reduction reaction, was successfully synthesized by a template replicating-assisted chemical vapor deposition (CVD) method. The obtained mesostructured WC/MG composite possesses high oxygen reduction reaction catalytic activity and stable electrochemical property. In O₂-staturated 0.1 mol/L KOH solution, the half-wave potential (E_1/2) and limiting current density of the sample WC/MG-900 annealed at 900℃ were only 50 mV and 0.2 mA/cm² lower than those of commercial Pt/C catalyst, respectively. Koutecky-Levich (K-L) plots and rotating ring-disk electrode (RDE) measurements indicated that the mesostructured WC/MG exhibited an approximate 4 e^- transfer pathway during the ORR process. The comparable ORR performance to Pt/C, long-lived electrochemical stability and excellent methanol tolerance make the synthesized mesostructured WC/MG composite a potential electrode catalyst in oxygen reduction reaction.

A series of nitrogen-doped diamond (NDD) film electrodes were synthesis by hot cathode direct current plasma chemical vapor deposition (HCDCPCVD) method with varied ratio CH₄/H₂/N₂ gas mixture. Morphologies of diamond films were characterized by SEM. Electrical and electrochemical properties of nitrogen-doped diamond electrodes were characterized by Hall test and cyclic voltammetry. The results show that when the nitrogen flow rate is less than 30 sccm, the conductivity of the film increases slightly with the increase of the nitrogen flow rate. As the nitrogen flow rate continues to increase, the conductivity decreases rapidly, showing the maximum electro- conductibility of 5.091 S/cm. The nitrogen-doped diamond electrode has good voltammetric performance with a wide potential window and a low background current in acidic, neutral and alkaline media. Properties of anodic oxidation degradation of nitrogen-doped diamond electrodes were tested using nitrobenzene as target pollutant. In the supporting electrolyte of 0.1 mol/L Na₂SO₄ solution, 0.5 mmol/L nitrobenzene is decomposed using the nitrogen- doped diamond as anode. After reaction for 300 min, degradation rate of the nitrobenzene reaches 94%, and COD (Chemical Oxygen Demand) removal rate is about 68%.

Surface modification of Fe₃N nanoparticles by KOH solution under electrification conditions was carried out, and effect of alkalization on the catalytic performance of Fe₃N nanoparticles was investigated. Morphology and composition of Fe₃N nanoparticles and alkalized Fe₃N nanoparticles were characterized by XRD, TEM, EDX, XPS, Raman spectra, and Fourier Transform Infrared spectroscopy. Electrocatalytic hydrogen evolution reaction (HER) performance of Fe₃N nanoparticles and alkalized Fe₃N nanoparticles was analyzed by time-current curve, linear sweep voltammetry, Tafel slope, AC impedance method, and CV curve. It was found that, for alkalized Fe₃N nanoparticles, their average grain sizes decreased from (80±10) nm to (70±10) nm. Their morphology changed from broken chain structure to elliptical structure, while their the phase changed partly from ε-Fe₃N to α-Fe₂O₃, which brought about more exposed electrocatalytic activity sites when compared with the Fe₃N before alkalization. Overpotential at 10 mA/cm² the alkalized Fe₃N nanoparticles was reduced from 0.429 V to 0.204 V and Tafel slope was reduced from 103 mV/dec to 95 mV/dec. Low opening voltage, small Tafel slope, low over-potential, small AC impedance and larg chemically active surface area were achieved by the alkalized Fe₃N nanoparticles, demonstrating that alkalized Fe₃N is a promising excellent electrocatalyst for water splitting.

By hydrothermal method using carbon sphere as template, single and double shell CeO₂ hollow spheres were prepared with specific surface area of 124.44 m²/g, 140.95 m²/g, pore volume of 0.014427 cm³/(g·nm), 0.018605 cm³/(g·nm), and pore size distribution in the range of 2 nm-4 nm. The Pt-CeO₂/RGO catalysts were prepared by microwave-assisted reduction of chloroplatinic acid using ethylene glycol, and then the effect of the addition of CeO₂ hollow sphere on the electrocatalytic performance of Pt-based catalysts were investigated. The microstructure and catalysts property of CeO₂ were characterized by X-ray diffraction (XRD), specific surface area and pore size analyzer (BET), scanning electron microscopy (SEM)-electron spectroscopy (EDAX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and the electrochemical performance of the catalysts was tested by electrochemical workstation. The results show that the CeO₂ in the catalyst maintains the original spherical morphology and the Pt nanoparticles are mainly distributed near the CeO₂. When RGO : CeO₂ = 1 : 2, the Pt-CeO₂/RGO catalyst with double shell CeO₂ hollow sphere shows the best electrocatalytic activity, with electrochemically active surface area at 94.27 m²/g, peak current density at 613.54 A/g, and the steady-state current density of 1000 s at135.45 A/g.

Cobalt sulfide nanomaterials are considered as important counter electrode materials for dye-sensitized solar cells. A potential reversal electrodeposition technique was applied to fabricate transparent cobalt sulfide film with fluorine-doped tin oxide glass as substrate. The experimental results demonstrate that the surface morphology of cobalt sulfide films is mainly dependent on the pH value of plating solution. The thickness of cobalt sulfide films can be effectively controlled by electrodeposition cycles. Then, cobalt sulfide films were used as counter electrodes of dye-sensitized solar cells. Electrochemical measurements prove that cobalt sulfide counter electrodes exhibit high electrocatalytic activity. In particular, under electrodeposition condition of pH 7.2 and 12 cycles, cobalt sulfide counter electrode composed of the nanosheet structure exhibits higher electrocatalytic activity than platinum electrode, due to the increase of electrocatalytic active sites. Meanwhile, remarkable photoelectrical conversion efficiency of the dye-sensitized solar cell based on cobalt sulfide counter electrode is up to 7.26% with an average value of 7.18% for ten devices, which is higher than that of the dye-sensitized solar cell equipped with platinum electrode (6.94%).

It is very difficult for single ceria to be used as an electrocatalyst because of its relatively poor electron conductivity and rare number of oxygen vacancy. Recently, it has been studied in the field of CO catalysis by doping transition metallic or non-metallic elements to improve the catalytic ability of ceria, while recent research has demonstrated that many oxides containing cobalt display better electrocatalytic activity. In this study cobalt doped ceria nanoparticles were prepared by homogeneous precipitation method. The electrochemical tests show that the optimum doping molar ratio is 20mol% for ORR and OER catalytic effect. After 10 hours of catalysis, the current density of ORR and OER decrease by about 20% and 5%, respectively, far below the corresponding values when noble metal and undoped cerium oxide nanoparticles were used as catalysts, and it indicated that the prepared catalyst owns good catalytic stability. In addition, XPS and other tests show that the decrease of charge transfer impedance (the improvement of electronic conductivity), the increase of active oxygen species, and the increased oxygen vacancies after doping are main reasons for improved catalytic performance. Therefore, doping cobalt greatly enhanced electrocatalytic properties of ceria nanoparticles are greatly enhanced by doping cobalt, providing guidence for other ionic conductors employed as bifunctional electrocatalysts.

Li-O₂ batteries are regarded as a promising energy storage system for their extremely high energy density. MnO₂-based materials are recognized as efficient and low-cost catalyst for a Li-O₂ battery positive electrode material. In this work, α-MnO₂ nanowires were successfully synthesized by a hydrothermal method and their electrocatalytic performance were investigated in Li-O₂ batteries. X-ray diffraction and field emission scanning electron microscope confirms the formation of α-MnO₂. The Li-O₂ battery which consists of α-MnO₂ nanowires shows a high discharge capacity up to 12000 mAh•g^-1 at a restrict voltage of 2.0 V with the current density of 100 mA•g^-1. When restricting the discharge capacity at 500 mAh•g^-1, it can operate over 40 cycles and exhibit good cycle stability. These results indicate that the α-MnO₂ nanowires can be used as positive electrode catalysts for Li-O₂ batteries.

A novel kind of electrocatalytic oxygen evolution catalyst was fabricated by introducing g-C₃N₄ ultrathin films onto the surface of attapulgite (ATP) via a simple in-situ depositing technique, combined with freeze-drying and programmed roasting process. The obtained product was identified as ATP/g-C₃N₄. In order to achieve the best catalyst, a series of ATP/g-C₃N₄ composites with different mass fraction of ATP were obtained and marked as ATP/g-C₃N₄-w, where w represents the mass fraction of ATP (w =mATP: (mATP + mg-C₃N₄)= 0.33, 0.40, 0.50, 0.67). Results show that g-C₃N₄ thin layers are uniformly loaded onto the ATP surface via the chemical bond (Si-O-C), which is beneficial to tailor the surface electronic structure of g-C₃N₄ and provide more active sites. Their electrocatalytic oxygen evolution properties in 0.1 mol/L KOH were investigated. It is found that ATP/g-C₃N₄-0.50 presents the best oxygen evolution catalytic performance and has excellent oxygen evolution stability. Its oxygen evolution over potential is 410 mV and the Tafel slope is 118 mV/dec at a current density of 10 mA/cm ². The results suggest that ATP/ g-C₃N₄-0.50 can be used as a potential oxygen evolution catalyst.

The nitrogen-doped porous carbon applied for oxygen reduction reaction (ORR) has aroused extensive interests due to its unique physical and chemical properties. However, the complicated nitrogen-doping strategy and high cost limit its extensive application. In this work, a series of nitrogen-doped porous carbons were prepared by a facile pyrolysis process coupling with subsequent KOH activation using renewable N-enriched biomass potato as carbon source. Effects of activation temperature and KOH amounts on the textural properties and electrocatalytic ORR activities of the final samples were investigated in detail. The KOH activation treatment results in a high specific surface area (SSA) and hierarchical porous structure, which is beneficial for improved ORR performance. The optimized NPC-750 possesses a high SSA of 1134.2 m ²?g ^-1, developed hierarchical pores as well as moderate nitrogen content (1.57at%). It also exhibits a positive onset potential of 0.89 V (vs. RHE) and half-wave potential of 0.79 V (vs. RHE). Simultaneously, the advanced long-time stability and methanol-tolerance capacity were also obtained, implying that these biomass-derived porous carbons are potential low-cost ORR electrocatalysts. Moreover, these porous carbons show great potential in various fields including supercapacitors, adsorption/separation, catalysis and batteries as well.