Efficient bubble/precipitate traffic enables stable seawater reduction electrocatalysis at industrial-level current densities
Jie Liang, Zhengwei Cai, Zixiao Li, Yongchao Yao, Yongsong Luo, Shengjun Sun, Dongdong Zheng, Qian Liu, Xuping Sun, Bo Tang
Abstract
Abstract Seawater electroreduction is attractive for future H 2 production and intermittent energy storage, which has been hindered by aggressive Mg 2+ /Ca 2+ precipitation at cathodes and consequent poor stability. Here we present a vital microscopic bubble/precipitate traffic system (MBPTS) by constructing honeycomb-type 3D cathodes for robust anti-precipitation seawater reduction (SR), which massively/uniformly release small-sized H 2 bubbles to almost every corner of the cathode to repel Mg 2+ /Ca 2+ precipitates without a break. Noticeably, the optimal cathode with built-in MBPTS not only enables state-of-the-art alkaline SR performance (1000-h stable operation at –1 A cm −2 ) but also is highly specialized in catalytically splitting natural seawater into H 2 with the greatest anti-precipitation ability. Low precipitation amounts after prolonged tests under large current densities reflect genuine efficacy by our MBPTS. Additionally, a flow-type electrolyzer based on our optimal cathode stably functions at industrially-relevant 500 mA cm −2 for 150 h in natural seawater while unwaveringly sustaining near-100% H 2 Faradic efficiency. Note that the estimated price (~1.8 US$/kg H2 ) is even cheaper than the US Department of Energy’s goal price (2 US$/kg H2 ).