"Nano-garden cultivation" for electrocatalysis: controlled synthesis of Nature-inspired hierarchical nanostructures

Three-dimensional intricate nanostructures hold great promise for real-life applications. Many of these hierarchical structures resemble shapes from Nature, demonstrating much improved physico-chemical properties. Yet, their rational design and controlled synthesis remain challenging. By simply manipulating (electro)chemical gradients using a combined hydrothermal and electrodeposition strategy, we herein show the controlled growth of Co(OH)₂ nanostructures, mimicking the process of garden cultivation. The resulting “nano-garden” can selectively contain different patterns, all of which can be fully phosphidated into CoP without losing the structural integrity. Remarkably, these CoP nanostructures show distinct catalytic performance in oxygen evolution and hydrogen evolution reactions. Under pH-universal conditions, the CoP “soil + flower-with-stem” structure shows a much more “effective” surface area for gas-evolving reactions with lower activation and concentration overpotentials. This provides superior bifunctional catalytic activity for both reactions, outperforming noble metal counterparts.