The production of green hydrogen by water electrolysis is often kinetically limited by the sluggish oxygen evolution reaction (OER) at the anode. Here, we prepared a bifunctional nickel foam supported NiFe₂O₄ spinel catalyst (i.e. NiFe₂O₄/NF) that is capable of facilitating the coupling of hydrogen evolution reaction (HER) with selective methanol oxidation reaction (SMOR) in seawater to produce formate via a CO-free pathway. At a cell potential of 2.0 V, the NiFe₂O₄/NF||NiFe₂O₄/NF catalyzed HER-SMOR system produces remarkably high current density (>800 mA cm⁻²) with high Faradaic efficiencies (FE) at both electrodes (>96 % for HER and >95 % for SMOR to formate). The NiFe₂O₄/NF||NiFe₂O₄/NF HER-SMOR system also exhibits excellent stability over 48 h of continuous operation. With H₂ being the only gaseous product, the HER-SMOR electrolysis system could operate in the absence of a membrane. Furthermore, the NiFe₂O₄/NF||NiFe₂O₄/NF electrodes are sufficiently robust for continuously catalyzing HER-SMOR in seawater electrolysis, showing no sign of deactivation or chlorine oxidation reactions over 6 h of continuous operation at a high current density of 700 mA cm⁻². Mechanistic investigation and DFT calculations reveal that SMOR proceeds via a CO-free pathway, with Ni and Fe as the active sites for methanol and OH activation, respectively.

通过水电解生产绿色氢气通常在动力学上受到阳极缓慢的析氧反应 (OER) 的限制。在这里，我们制备了一种双功能镍泡沫负载 NiFe ₂ O ₄尖晶石催化剂（即 NiFe ₂ O ₄ /NF），该催化剂能够促进海水中的析氢反应（HER）与选择性甲醇氧化反应（SMOR）的耦合，以生产甲酸通过无 CO 途径。在 2.0 V 的电池电位下，NiFe ₂ O ₄ /NF||NiFe ₂ O ₄ /NF 催化的 HER-SMOR 系统产生非常高的电流密度（>800 mA cm ^-2) 在两个电极上都具有高法拉第效率 (FE)（HER 大于 96%，SMOR 生成甲酸盐大于 95%）。NiFe ₂ O ₄ /NF||NiFe ₂ O ₄ /NF HER-SMOR 系统在连续运行 48 小时后也表现出出色的稳定性。由于 H ₂是唯一的气态产物，HER-SMOR 电解系统可以在没有膜的情况下运行。此外，NiFe ₂ O ₄ /NF||NiFe ₂ O ₄ /NF 电极足够坚固，可在海水电解中连续催化 HER-SMOR，在高电流下连续运行 6 小时后没有显示失活或氯氧化反应的迹象密度为 700 mA cm^-2。机理研究和 DFT 计算表明，SMOR 通过无 CO 途径进行，Ni 和 Fe 分别作为甲醇和 OH 活化的活性位点。