Pd supported on carbon containing nickel, nitrogen and sulfur for ethanol electrooxidation

Abstract

Fuel cells are widely recognized as very attractive devices to obtain directly electric energy through an electrochemical reaction between anode and cathode 1 . Among the power sources, direct methanol fuel cells (DMFCs) have been extensively investigated and proposed to be used as mobile applications 2 . Compared to methanol, ethanol is a promising alternative fuel with less toxicity. Direct ethanol fuel cells (DEFCs) have been extensive studied by many research groups [3][4][5][6] . As emerging technologies, DEFCs have many challenges that need to be addressed. One of the major hurdles of the DEFCs is the ethanol electrooxidation reaction which exists slow sluggish kinetics due to the twelve-electron transfer process 7,8 . Platinum (Pt) and Pt-based nanoparticles have been generally used as the acceptable anode materials for the electrooxidation of liquid fuels such as methanol and ethanol 9-11 . Unfortunately, high cost and susceptible to poisoning by CO make it practically impossible to be an ideal candidate at a commercial level. Therefore, exploring cost-effective and catalytically active materials is of great interest to study.Compared with Pt, palladium (Pd) has numerous advantages in the DEFCs 9,10,12-15 . Xu and Shen 9,16 firstly found that Pd-based catalysts have remarkable activity for ethanol oxidation in alkaline media in 2006. However, it is still necessary to decrease the dosage of Pd and lower the catalyst cost. Lots of methods have been proposed such as modifying Pd particles with transition metal oxides including NiO, MnO 2 , MoO 3 , CeO 2 , Co 3 O 4 , CuO and TiO 2 10, [16][17][18][19] . Among such transition metal oxides, NiO nanoparticles can improve the oxidation kinetics and reduce the poisoning of Pd/C, due to the excellent capacity to transport surface lattice oxygen and OH ads 10,20,21 . However, general routes to synthesize NiO nanoparticles are usually on the surface of carbon materials, which lead to heterogeneous dispersion and even result in the surface shed off. Thus, it is urgent to choose a template to arrange the growth of transition metal oxides. Recently, porous carbon materials synthesized by directly annealing coordination compounds especially metal-organic frameworks (MOFs) possess ultrahigh surface area and periodic network of highly ordered three-dimensional framework structure, which are highly desirable as stable supports to load precious metals [22][23][24][25] .Here, we used the vanillic thiosemicarbazone ligand (L = C 9 H 10 N 3 O 2 S) including N and S heteroatoms and its coordination compound NiL 2 as precursors to obtain porous carbon materials containing nickel, nitrogen and

Catalytic Activity Boosting of Nickel Sulfide toward Oxygen Evolution Reaction via Confined Overdoping Engineering

“…Unlike the results shown in Table S1, no Si is found, and the element ratios are different because XPS is a general surface analysis tool, while its penetration depth is rather limited in comparison with EDS. The C 1s peaks of the three samples shown in 28,29 The high content of graphitic C is in agreement with the XRD and Figure 2b,c. The ratios of different types of carbon are shown in Table S4.…”

“…Both the EDS (Table S1) and XPS results (Figure S7a and Table S3) showed that the mesoporous carbon substrate is nitrogen-doped, with the atomic ratio ranging from 1.1% to 3.6%. The N 1s core spectra (Figure S7c) show that the element N exists in the forms of pyridinic N (398 eV), pyrrolic N (400 eV), graphitic N (401 eV), and oxidized N (403 eV). − The graphitic N could improve the electrical conductivity of the carbon substrate, while pyridinic N and pyrrolic N could serve as metal-coordination sites. It is widely accepted that graphitic-N could increase the limiting current density, while pyridinic-N could improve the onset potential for the OER .…”

Toward Overcoming the Challenges in the Comparison of Different Pd Nanocatalysts: Case Study of the Ethanol Oxidation Reaction

“…This is relevant to study and optimize the electrocatalytic activity and stability for the EOR [33] but also other alcohols oxidation [57,63,64] or alternative reactions where Pd is key [65]. The effect of support [66], loading [58], different electrochemical testing protocols including an "activation procedure" or longer tests [21,52], different electrolytes [67], the effect of adding surfactant to the catalyst [20], and ink composition [68] are all important parameters to understand in order to rationally design improved supported catalysts [37]. With the simple systems and approach presented, all these parameters can be systematically addressed and studied in greater detail.…”

Nitrogen‐ and carbon‐richNi2O3nanolayer shieldedNi3Celongated square bipyramidal‐like nanostructures for hybrid supercapacitors

“…In Figure 3B, the intense peaks appeared at 1343.9 and 1579.2 cm À1 represent the D-band and G-band, respectively. 46 The D-band is the result of a defective graphitic structure, and the G-band represents highly ordered lattice of bonded carbon atoms. 47 The additional peaks at the wavelengths of ~520 and 1082 cm À1 correspond to SiO 2 and Si of silicon substrate, respectively, because the sample powder was placed on the silicon substrate.…”