Surface Engineering of Porphyrin Coordination on a Carbon Nanotube for Efficient Hydrogen Evolution

Graphical HER electrocatalysis : We developed a novel Pt(II)-porphyrin based catalyst for HER electrocatalysis, its optimised performance can be quantitatively designed in molecular level. The optimized Pt(II)-porphyrin loading and precisely morphology control could be fine-tuned and quantitatively premeditated by using fluorescence and UV-vis titration based on the unique π–π interactions behaviour of the porphyrin. This study provides a new approach for preparing a highly active and stable HER catalyst, which could potentially be extended to other reactions to improve the utilization efficiency of precious metal catalysts. Functionalised porphyrins have attracted considerable attention owing to their ability to coordinate with numerous metal ions. We design and synthesize a novel composite system based on functionalised Pt(II)-porphyrin and multiwalled carbon nanotubes for hydrogen evolution reaction (HER) electrocatalysis. Rather than qualitatively integrating porphyrin with carbon nanotubes, the optimized Pt(II)-porphyrin loading and precisely morphology control could be fine-tuned and quantitatively premeditated by using fluorescence and UV-vis titration based on the unique π–π interactions behaviour of the porphyrin for the first time. The as-prepared composites exhibit superior HER catalytic activity with an overpotential of 35 mV for an electrocatalytic current density of j=−10 mA cm −2 and a Tafel slope of 32.3 mV dec −1 . Moreover, such catalysts do not exhibit observable activity decay after a 1000-cycle stability test, thus demonstrating their excellent durability. To further reduce Pt loading to achieve cost efficiency, we develop a Pt−Co bimetallic HER catalyst with an ultra-low platinum content through a straightforward synthesis pathway with high catalytic activity and stability. This study provides a new approach for preparing a highly active and stable HER catalyst, which could potentially be extended to other reactions to improve the utilization efficiency of precious metal catalysts.