A Multi-Bioinspired Dual-Gradient Electrode for Microbubble Manipulation toward Controllable Water Splitting.

Clean energy generated from total water splitting is expected to be an affordable, sustainable, and reliable resource but it remains a challenge to gain pure fuel with a controllable pathway. Here, a simple and economical strategy that enables in situ separation of H /O product by manipulating the generated gas phases with the aid of multi-bioinspired electrodes is proposed. This versatile electrode is based on a Janus asymmetric foam with dual gradients, i.e., the wettability gradient promotes the one-way gas penetration and the geometry gradient boosts the spontaneous on-surface transport in the horizontal direction, which cooperatively facilitates self-driven 3D bubble transport in an aqueous environment. Benefitting from the 3D bionic electrode, the limited distance between the cathode and the anode can be reduced to 1 mm, and the corresponding current density is enhanced 1.5 times as compared with the common condition. This Janus triangular electrode with dual directionality elucidates 3D smart bubble manipulation during overall water splitting and should offer a great opportunity to develop advanced electrochemical processes toward complicated environments such as confined space and zero gravity.