Manageable Bubble Release Through 3D Printed Microcapillary for Highly Efficient Overall Water Splitting.

Porous metal foams (e.g., Ni/Cu/Ti) are applied as catalyst supports extensively for water splitting due to their large specific area and excellent conductivity, however, intrinsic bubble congestion is unavoidable because of the irregular three-dimensional (3D) networks, resulting in high polarization and degraded electrocatalytic performances. To boost the H 2 O decomposition kinetics, the immediate bubble removal and water supply sequential in the gas-liquid-solid interface is essential. Inspired by the high efficiency of water/nutrient transport in the capillaries plants, this work designs a graphene-based capillary array with side holes as catalyst support to manage the bubble release and water supply via a Z-axis controllable digital light processing (DLP) 3D printing technology. Like planting rice, a low-cost, high-active CoNi carbonate hydroxide (CoNiCH) is planted on support. A homemade cell can reach 10 mA cm -2 in 1.51 V, and be kept at 30 mA cm -2 for 60 h without noticeable degradation, surpassing most of the known cells. This research provides a promising avenue to design and prepare advanced catalysts in various fields, including energy applications, pollutant treatment, and chemical synthesis.