Noble Metal Nanoparticles/n-doped Three-dimensional Crosslinked Graphene Composites: Preparation And Electrochemical Application

Noble metal nanocatalyst has broad prospect because of thier high catalytic activity and good chemical stability,however,the scarcity,high cost,and aggregating properties limit thier application.Generaly,an appropriate support can promote the dispersion of noble metal nanomaterials and improve their utilization.Moreover,the synergistic effect between the functional support and the noble metal can enhace their catalytic activity.Here,the robust N-doped three dimensional crosslinked graphene?R3DNG?was firstly fabricated using graphene oxide?GO?,formaldehyde,and melamine as raw materials through the simple hydrothermal and self-assembly strategy.Noble metal nanoparticle/R3DNG composites were subsequently prepared to explore their electrochemical application.Firstly,Pt nanoparticles/R3DNG composite?PtNPs/R3DNG?was prepared,and its electrocatalytic activity for methanol oxidation was investigated in acidic medium.The composite holds typicaly three-dimensional hierarchically porous structure.PtNPs are uniformly distributed on the surface of R3DNG with the average diameter of 2.5 nm.The total BET surface area is 314.8 m² g^-1,and the total pore volume is 1.16cm³ g^-1.The electrochemically active surface area?ECSA?of this composite achieves 45.8 m² g^-1,which is much higher than that of commercial Pt/C catalyst(30.8 m² g^-1).As electrocatalyst for methanol oxidation,PtNPs/R3DNG exhibits 2.8 times anodic peak current?1.63 A mg^-11 Pt?to that of commercial Pt/C(0.58 A mg^-1 Pt).The high catalytic activity,excellent resistance to poisoning,and outstanding cycling stability of PtNPs/R3DNG make it a promosing electrocatalyst for methaonol electro-oxidation.Secondly,Pd nanoparticles/R3DNG composite?PdNPs/R3DNG?was prepared and explored as the electrocatalyst for glucose oxidation.The composite shows three-dimensional porous structure.PdNPs were homogeneously loaded on the surface of R3DNG.PdNPs has the average size of 3.2 nm.The composite presents the total BET surface area of 252.3m² g^-1,and the total pore volume of 2.08 cm³ g^-1.In alkaline solution,PdNPs/R3DNG exhibits good electrocatalytic activity for glucose oxidation.Thenon-enzymaticglucoseelectrochemicalsensorbasedon PdNPs/R3DNG has wide linear detection ranges.The first linear range is from 1 mM to 10 mM?R²=0.9964?with the sensitivity of 17.4?A mM cm^-2.The second linear range is from 11 mM to 24mM?R²=0.9964?with the sensitivity of 7.36?A mM cm^-2.The electrochemical sensor shows excellent performance in terms of reproducibility,stability and anti-jamming capability.Finally,Ru nanoparticle/R3DNG composite?RuNPs/R3DNG?was prepared and its catalytic performance for electrochemical hydrogen evolution reaction?HER?and oxygen evolution reaction?OER?was researched.The composite possesses three-dimensional porous structure,RuNPs were uniformly supported on the surface of R3DNG,and has an average particle size of 3.8 nm.When using electrocatalyst for HER and OER,RuNPs/R3DNG has an small HER overpotential of 30 mV at the current density of 10 mV cm^-2 and a low tafel slope of 39.9 mV dec^-1,and the OER overpotential of 250 mV with the tafel slope of 73 mV dec^-1 in acidic solution,while has the HER overpotential of 128 mV with the tafel slope of 87.7 mV dec^-1,and the OER overpotential of 280 mV with the tafel slope of 79 mV dec^-1 in alkaline solution.The composite only has 8 mV(100mV cm^-2)overpotential decay after 20,000 cycles.The results proved that RuNPs/R3DNG composites are excellent electrochemical HER and OER bifunctional catalysts.