Defect-rich low-crystalline Rh metallene for efficient chlorine-free H2 production by hydrazine-assisted seawater splitting

Seawater splitting is considered as a promising way to replace water splitting for H2 production due to the enrichment of seawater resources. However, the development of this technology has been greatly hampered by the lack of efficient electrocatalysts and the detrimental effects of chlorine electrochemistry. Herein, we report a defect-rich low-crystalline Rh metallene (l-Rh metallene) with an amorphous/crystalline hetero-phase structure for seawater electrolysis, where chlorine generation is avoided by replacing the oxygen evolution reaction (OER) with the hydrazine oxidation reaction (HzOR). Benefiting from the large surface-to-volume ratio, abundant active sites and unique electronic structure, the l-Rh metallene exhibits out-standing catalytic activity for both hydrogen evolution reaction (HER, −38 mV at 10 mA cm−2) and HzOR (−2 mV at 10 mA cm−2). Notably, an ultra-low voltage of only 28 mV is required to achieve 10 mA cm−2 in two-electrode hydrazine-assisted seawater splitting system.