Structural Buffer Engineering on Metal Oxide for Long‐Term Stable Seawater Splitting

Abstract

Seawater electrolysis is an attractive technique for massive green hydrogen production owing to the dominant advantages of seawater resources, namely low‐cost and limitlessness. However, the oxygen evolution reaction (OER) catalysts will be easily deactivated for severe seawater Cl− permeation and corrosion. Herein, a structural buffer engineering strategy is reported to endow the Co2(OH)3Cl with long‐term operation stability and a high OER selectivity of ≈99.6% in seawater splitting. The lattice Cl− of Co2(OH)3Cl can act as the structural buffer, whose continuous leaching during OER can leave vacancies for seawater Cl− invasion, so as to avoid catalyst deactivation. Accordingly, Co2(OH)3Cl can maintain 99.9% of its initial current density after 60 000 s operation, while that of Co(OH)2 decays by 52.7% in 7 000 s. Meanwhile, the lattice Cl− of Co2(OH)3Cl can optimize the binding energy of reaction intermediates on the neighboring OCoO site. Thus, Co2(OH)3Cl exhibits a current density of 330.5 mA cm–2 at the potential of 1.63 V versus RHE, 45.9 times higher than that of Co(OH)2. The structural buffer strategy may be applied to incorporate other metal oxides with suitable anions, and effectively boost their OER activity and stability in alkaline seawater.

Recent advances in transition metal‐based electrocatalysts for seawater electrolysis

“…For example, Zhuang et al reported a structural buffer strategy to effectively avoid the negative effect of chloride ions invasion and boost OER activity (Figure 11A), which could be demonstrated by the comparison of Co 2 (OH) 3 Cl and Co(OH) 2 (Figure 11B, C). 66 Typically, DFT study further verified the crucial role in corrosion resistance and performance enhancement capability of the lattice Cl À species, which was based on the two CER reaction pathways. In addition, intermediate (Cl à ) on the site of O-Co-Cl with stronger adsorption strength proved that O-Co-Cl sites tend to be preferential CER reaction sites (Figure 11D-H).…”

“…To combat serious environmental pollution and energy crisis, renewable clean energy H 2 has attracted wide attention, and seawater with abundant reserves is Reproduced with permission from reference [66]. Copyright 2022, Wiley-VCH.…”

“…(F‐H) Energy profiles for CER‐1, CER‐2, and OER, respectively. Reproduced with permission from reference [66]. Copyright 2022, Wiley‐VCH.…”

Rapid “self-healing” behavior induced by chloride anions to renew the Fe–Ni(oxy)hydroxide surface for long-term alkaline seawater electrolysis

“…This is due to the vacancy formed by the continuous leaching of Cl − of Co 2 (OH) 3 Cl in the OER process, which could become the preferred attack site of Cl − in seawater to avoid the structural collapse of the catalyst. 22 Fe-Ni(oxy)hydroxide is the most important active species in the Adsorbate Evolution Mechanism (AEM). 23,24 But now the research difficulty of Fe-Ni(oxy)hydroxide is how to prepare it quickly, modify its catalytic surfaces accurately, and maintain its catalytic activity for a long time.…”

“…This is due to the vacancy formed by the continuous leaching of Cl − of Co 2 (OH) 3 Cl in the OER process, which could become the preferred attack site of Cl − in seawater to avoid the structural collapse of the catalyst. 22…”