Self-assembled pearl-bracelet-like CoSe2-SnSe2/CNT hollow architecture as highly efficient electrocatalysts for hydrogen evolution reaction

For the first time, self-assembled pearl-bracelet-like CoSe2-SnSe2/CNT hollow nanoboxes (CSCB), as a novel non-precious electrocatalyst for hydrogen evolution reaction (HER), have been synthesized by a facile aqueous reaction and selenization processes. Compared to bare CoSe2-SnSe2 nanoboxes (CSB), the CSCB hybrid shows much faster kinetics and far better HER performance: the HER mechanism of CSCB is improved to be a Volmer-Tafel combination, instead of Volmer-Heyrovsky combination (as in case of CSB); the Tafel slope of CSCB dramatically decreases from 74.5 mV dec(-1) (for CSB) to 32.4 mV dec(-1), which nearly approaches to that of the commercial Pt/C electrocatalyst; the CSCB hybrid delivers a very large current density of 35 mA cm(2) at -250 mV vs. RHE, over 85 times larger than that of CSB (0.4 mA cm(-2)). Furthermore, CSCB shows an excellent long-term electrocatalytic stability even after 1500 cycles. The superior HER performances of CSCB can be attributed to its well-designed pearl-bracelet-like hollow architecture with high conductivity and rich porosity: the CNT chains with a good mechanical strength and high conductivity construct a highly conductive network for fast charge transportation during HER; the hollow CoSe2-SnSe2 nanoboxes with large internal voids and rich nano-/mesopores provide abundant catalytic active sites and facilitate ion-diffusion. This study provides insight into a rational design and low-cost synthesis of the non-precious transition-metal chalcogenide-based electrocatalysts with high efficiency and stability for HER.