A General Synthesis of Crystal Phase Controllable Aerogels for Efficient Hydrogen Evolution

Amorphous/crystalline (a/c) hetero-phase structures are considered as a class of efficient electrocatalysts for hydrogen evolution reaction (HER), but it remains a substantial challenge to obtain the specific phase by phase-selective synthesis. In this work, a general route for the preparation of various heterogeneous aerogels (RuB, PtB, PdB, and RhB) consisting of amorphous and crystalline phases is presented through a controlled NaBH₄ reduction method. The prepared a/c-RuB aerogel exhibits better HER performance due to their desirable compositional and structural advantages such as more exposed active sites, optimized electronic structure, and interfacial synergistic effects. It requires only a low overpotential of 39 mV to reach a density of 10 mA cm^-2 and also exhibits excellent stability. This work provides a new phase-selective synthesis strategy for the design and development of advanced hetero-phase electrocatalysts.