Among various types of clean energy sources, hydrogen is considered promising due to its high energy density, zero carbon emission during combustion. [4][5][6] To fully deploy technologies for hydrogen production, there is a critical need for the selection of efficient hydrogen evolution reaction (HER) catalysts. [7][8][9] Many researchers focus on producing cost-effective Pt-based catalysts by enhancing the active sites of the Pt (e.g., single atom-based catalysts) and distribution of the Pt in the supports, which can largely decrease the amount of Pt. [10][11][12][13] However, up to date, it is still a major challenge to stabilize Pt nanoclusters during the HER. [14,15] 1D or 2D nanostructures can have large surface energy, spatial confinement, and tunable imperfections, which endow them with unique properties, such as increased catalytic activity, enhanced mechanical strength, and chemical stability. [16][17][18][19] Combining 0D Pt nanocluster with 1D/2D nanostructures can prevent their aggregation and mass loss in catalytic recycling. [20] Until now, considerable efforts have focused on developing low-dimensional heterostructures. [21,22] Carbon nanofibers (CNFs) possess unique mechanical, thermal, and Large scale solar-driven hydrogen production is a crucial step toward decarbonizing society. However, the solar-to-hydrogen (STH) conversion efficiency, long-term stability, and cost-effectiveness in hydrogen evolution reaction (HER) still need to be improved. Herein, an efficient approach is demonstrated to produce low-dimensional Pt/graphene-carbon nanofibers (CNFs)-based heterostructures for bias-free, highly efficient, and durable HER. Carbon dots are used as efficient building blocks for the in situ formation of graphene along the CNFs surface. The presence of graphene enhances the electronic conductivity of CNFs to ≈3013.5 S m −1 and simultaneously supports the uniform Pt clusters growth and efficient electron transport during HER. The electrode with a low Pt loading amount (3.4 µg cm −2 ) exhibits a remarkable mass activity of HER in both acidic and alkaline media, which is significantly better than that of commercial Pt/C (31 µg cm −2 of Pt loading). In addition, using a luminescent solar concentrator-coupled solar cell to provide voltage, the bias-free water splitting system exhibits an STH efficiency of 0.22% upon one-sun illumination. These results are promising toward using low-dimensional heterostructured catalysts for future energy storage and conversion applications.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smtd.202101470.
