The corrosion inhibition of metallic substrates is a prime issue for many potential applications where corrosion plays a crucial role. The development of carbon based on functionalized coatings could increase the life...The corrosion inhibition of metallic substrates is a prime issue for many potential applications where corrosion plays a crucial role. The development of carbon based on functionalized coatings could increase the lifetime of metallic substrates by inhibiting the corrosion process. Present work is an effort to develop a corrosion inhibiting composite coating of graphene oxide and polypyrrole for AISI （American Iron and Steel Institute） type 304 stainless steel substrates. The electrochemical galvanostatic deposition process was applied for coating development. The coating morphology and ability to cover the substrate surface was analyzed with a high-resolution scanning electron microscope. The coating＇s structural and electronic properties were analyzed with Raman spectroscopy. The investigation of corrosion inhibition involved open circuit potential, Tafel, and voltammetry analysis. The standard salt test ASTM （American Society for Testing and Materials） G48A for stainless steel substrate has also been studied. Significant enhancement of corrosion potential as well as pitting potential for the composite coated substrates has been noted. Furthermore, corrosion and breakdown potential increased upon changing the material from graphene oxide to its composite coating. During the salt test analysis, the durability of the composite coating was noted up to 72 h, which is the standard time scale. Based on experimental analysis, this composite material can be used as an effective carbon based on functionalized corrosion inhibitor for stainless steel substrates to increase their lifetime.展开更多
Developing non-precious metal-based inexpensive and highly active electrocatalysts for the oxygen reduction reaction(ORR)in alkaline media is important for fuel cell applications.Herein,we report a simple and effectiv...Developing non-precious metal-based inexpensive and highly active electrocatalysts for the oxygen reduction reaction(ORR)in alkaline media is important for fuel cell applications.Herein,we report a simple and effective synthesis of transition-metal-doped zeolitic imidazolate framework-8(ZIF-8)and carbon nanotube(CNT)composite catalysts(ZIF-8@CNT)prepared via high-temperature pyrolysis at 900℃.The catalysts were characterized using different physicochemical techniques and employed as cathode materials in anion exchange membrane fuel cells(AEMFC).The prepared metal-free(ZNT-900),single-metal-doped(Fe-ZNT-900,Co-ZNT-900)and binary-metal-doped(Fe_(1)Co_(1)-ZNT-900,Fe_(1)Co_(2)-ZNT-900)catalysts had a sufficient amount of N-doping with the presence of FeCo moieties in the carbon skeleton of the latter two materials.N_(2) adsorption–desorption isotherms showed that all the prepared catalysts possess a sufficient Brunauer–Emmett–Teller surface area with more micropores present in ZNT-900,while a combined micro–mesoporous structure was obtained for transition-metal-doped catalysts.Binary-metal-doped catalysts showed the highest number of ORR-active sites(pyridinic-N,pyrrolic-N,graphitic-N,M–Nx)and exhibited a half-wave potential(E_(1/2))of 0.846 and 0.847 V vs.RHE for Fe_(1)Co_(1)-ZNT-900 and Fe_(1)Co_(2)-ZNT-900,respectively,which surpassed that of the commercial Pt/C catalyst(E_(1/2)=0.834 V).In H_(2)–O_(2) AEMFCs,the Fe_(1)Co_(2)-ZNT-900 catalyst delivered a maximum power density(P_(max))of 0.171 W cm^(-2) and current density at 0.5 V(j_(0.5))of 0.326 A cm^(-2),which is very close to that of the Pt/C catalyst(P_(max)=0.215 W cm^(-2) and j_(0.5)=0.359 A cm^(-2)).The prepared ZIF-8@CNT catalysts showed remarkable electrocatalytic ORR activity in 0.1 M KOH solution and fuel cell performance comparable to that of the benchmark Pt/C catalyst.展开更多
文摘The corrosion inhibition of metallic substrates is a prime issue for many potential applications where corrosion plays a crucial role. The development of carbon based on functionalized coatings could increase the lifetime of metallic substrates by inhibiting the corrosion process. Present work is an effort to develop a corrosion inhibiting composite coating of graphene oxide and polypyrrole for AISI （American Iron and Steel Institute） type 304 stainless steel substrates. The electrochemical galvanostatic deposition process was applied for coating development. The coating morphology and ability to cover the substrate surface was analyzed with a high-resolution scanning electron microscope. The coating＇s structural and electronic properties were analyzed with Raman spectroscopy. The investigation of corrosion inhibition involved open circuit potential, Tafel, and voltammetry analysis. The standard salt test ASTM （American Society for Testing and Materials） G48A for stainless steel substrate has also been studied. Significant enhancement of corrosion potential as well as pitting potential for the composite coated substrates has been noted. Furthermore, corrosion and breakdown potential increased upon changing the material from graphene oxide to its composite coating. During the salt test analysis, the durability of the composite coating was noted up to 72 h, which is the standard time scale. Based on experimental analysis, this composite material can be used as an effective carbon based on functionalized corrosion inhibitor for stainless steel substrates to increase their lifetime.
基金The present work was financially supported by the Estonian Research Council(grants PRG723,PRG4 and PRG1509).
文摘Developing non-precious metal-based inexpensive and highly active electrocatalysts for the oxygen reduction reaction(ORR)in alkaline media is important for fuel cell applications.Herein,we report a simple and effective synthesis of transition-metal-doped zeolitic imidazolate framework-8(ZIF-8)and carbon nanotube(CNT)composite catalysts(ZIF-8@CNT)prepared via high-temperature pyrolysis at 900℃.The catalysts were characterized using different physicochemical techniques and employed as cathode materials in anion exchange membrane fuel cells(AEMFC).The prepared metal-free(ZNT-900),single-metal-doped(Fe-ZNT-900,Co-ZNT-900)and binary-metal-doped(Fe_(1)Co_(1)-ZNT-900,Fe_(1)Co_(2)-ZNT-900)catalysts had a sufficient amount of N-doping with the presence of FeCo moieties in the carbon skeleton of the latter two materials.N_(2) adsorption–desorption isotherms showed that all the prepared catalysts possess a sufficient Brunauer–Emmett–Teller surface area with more micropores present in ZNT-900,while a combined micro–mesoporous structure was obtained for transition-metal-doped catalysts.Binary-metal-doped catalysts showed the highest number of ORR-active sites(pyridinic-N,pyrrolic-N,graphitic-N,M–Nx)and exhibited a half-wave potential(E_(1/2))of 0.846 and 0.847 V vs.RHE for Fe_(1)Co_(1)-ZNT-900 and Fe_(1)Co_(2)-ZNT-900,respectively,which surpassed that of the commercial Pt/C catalyst(E_(1/2)=0.834 V).In H_(2)–O_(2) AEMFCs,the Fe_(1)Co_(2)-ZNT-900 catalyst delivered a maximum power density(P_(max))of 0.171 W cm^(-2) and current density at 0.5 V(j_(0.5))of 0.326 A cm^(-2),which is very close to that of the Pt/C catalyst(P_(max)=0.215 W cm^(-2) and j_(0.5)=0.359 A cm^(-2)).The prepared ZIF-8@CNT catalysts showed remarkable electrocatalytic ORR activity in 0.1 M KOH solution and fuel cell performance comparable to that of the benchmark Pt/C catalyst.
