Coupling 0D and 1D carbons for electrochemical hydrogen production promoted by a percolation mechanism

Developing hydrogen evolution reaction (HER) electrocatalysts with high activity, durability and moderate price is essential for sustainable hydrogen energy utilization. Here, the facile coupling of carbon dots (CDs, 0D carbon materials) and carbon fibres (CFs, 1D carbon materials) for enhanced electrochemical hydrogen production was demonstrated. Electrochemical tests revealed that the CD/CF catalysts showed outstanding catalytic activity with a small overpotential of 280 mV at the current density of 10 mA cm<,sup>-2, a small Tafel slope of 87 mV dec^-1 and prominent durability. Percolation theory was for the first time introduced to interpret the catalytic mechanism of the CD/CF catalysts. The special morphology assembled by the 0D carbons constituted the percolating clusters and promoted electron transport throughout the 1D carbons. The strategy and theory can be adapted to general electrocatalytic applications for achieving and interpreting precise tuning on highly efficient electron transfer in electrocatalysts.