Efficient electrocatalytic proton reduction on CoP nanocrystals embedded in microporous P, N Co-doped carbon spheres with dual active sites

• Published in: Carbon (New York) 2020-01, Vol.156, p.529-537
• Main Authors: Boppella, Ramireddy, Park, Jaemin, Yang, Wooseok, Tan, Jeiwan, Moon, Jooho
• Format: Article
• Language: English
• Subjects: Carbon; Electroactivity; Electrocatalysis; Electrocatalysts; Electrolysis; Electrolytes; Hydrogen evolution reactions; Nanocrystals; Protons; Structural hierarchy; Sulfuric acid; Surface area
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2019.09.082

A facile and scalable method is reported to develop CoP nanocrystals encapsulated in a P, N co-doped C matrix (PNC) as a highly efficient electrocatalyst for hydrogen evolution reaction (HER) in acidic and basic media. The synthesized CoP-PNC electrocatalysts exhibit large specific surface area of 1543 m2 g−1, hierarchical microporous structure, and high density of surface -active sites. The porous CoP-PNC electrocatalysts exhibit excellent HER electroactivity, delivering a current density of 10 mA cm−2 at very low overpotentials of 87 and 106 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively. This remarkable HER performance mainly arises from the synergic effect between CoP and P, N co-doped C, high density of active sites and large surface area due to the multiple pore structures. Most importantly, the CoP-PNC retains high stability even after 40 h of continuous electrolysis in extremely acidic (pH = 0) and basic solutions (pH = 14). Cobalt phosphide (CoP) nanocrystal-encapsulated P, N co-doped porous carbon (PNC) was fabricated through one-step pyrolysis (CoP-PNC) using cobalt-chelated phytic acid in the presence of ammonium chloride. The synthesized CoP-PNC had a microporous structure with a large specific surface area, a high density of surface active sites, and excellent electrocatalytic activity and durability for the hydrogen evolution reaction. [Display omitted] •CoP nanocrystals encapsulated in P, N co-doped porous carbon matrix (CoP-PNC) are synthesized.•CoP-PNC possess large surface area, hierarchical microporous structure, and high density of surface-active sites.•CoP-PNC exhibits excellent hydrogen evolution activity and stability in both acidic and basic medium.