Highly Efficient Electrocatalytic Hydrogen Production over Carbon Nanotubes Loaded with Platinum Nanoparticles Using Solution Processing

Abstract Proton exchange membrane (PEM) electrolyzers are used for hydrogen (H₂) production by water electrolysis. The commercial cathodic electrocatalyst for this process is typically mechanically mixed platinum on carbon (Pt/C). However, aggregation of the platinum (Pt) makes high loading of the catalyst difficult. Therefore, a method for the homogeneous combination of Pt and carbon materials is required. Herein, the first example of a highly efficient single‐walled carbon nanotube (SWCNT) cathodic H₂‐production electrocatalyst that is loaded with platinum nanoparticles (PtNPs) using a newly developed suspension method is reported. Combining SWCNTs lapped with a water‐soluble, thiol‐functionalized polymer with PtNPs in water yields a PtNP‐conjugated SWCNT suspension. The electrocatalyst exhibits a low overpotential of 47 mV at a current density of 10 mA cm⁻² toward H₂ evolution in 0.5 m sulfuric acid. A PEM electrolyzer fabricated using the optimally prepared electrocatalyst with the low loading of 15 µg_Pt cm⁻² shows a high mass activity of 27 200 A g_Pt⁻¹, which is 80 times that of Pt/C with a loading amount of 2.8 mg_Pt cm⁻² (324 A g_Pt⁻¹). In addition, the PEM electrolyzer produces H₂ at a Faradaic efficiency of 97% and operates stably for 150 h at 100 mA cm⁻².