Polypyrrole encapsulating TiB2 as newly-emerged electrocatalyst for highly boosted hydrogen evolution reaction

Ceramic TiB2, a layered metal diboride with remarkable conductivity and chemical stability, are potential electrocatalyst towards hydrogen evolution reaction (HER). However, high overpotential (>1 V) is required for pristine TiB2 to drive water splitting, which is less than satisfactory in future hydrogen economy. Herein, conductive polypyrrole (PPy) encapsulating TiB2 (TiB2@PPy) has been developed via vapor phase polymerization, as the electrocatalyst for HER. Theoretically, the PPy shell serves both as electron-transfer channels to accelerate electron migration, and as Mott-Schottky centre to modify the electronic structure of TiB2. Beneficially, more improved HER performance has been achieved with the overpotential of 432 mV at 10 mA cm(-2), superior to that of pristine TiB2 (848 mV at 10 mA cm(-2)). Moreover, excellent stability is presented during 1000 CV cycles and 10 h constant evaluation. Our study provides a new avenue to create efficient HER electrocatalyst via conductive PPy engineering.