Fluoride-Induced Dynamic Surface Self-Reconstruction Produces Unexpectedly Efficient Oxygen-Evolution Catalyst

The oxygen-evolution reaction (OER) is a key process in water-splitting systems, fuel cells, and metal-air batteries, but the development of highly active and robust OER catalyst by simple methods is a great challenge. Here, we report an in situ dynamic surface self-reconstruction that can dramatically improve the catalytic activity of electrocatalysts. A fluoride (F-)-incorporating NiFe hydroxide (NiFe-OH-F) nanosheet array was initially grown on Ni foam by a one-step hydrothermal method, which requires a 243 mV over-potential (eta) to achieve a 10 mA cm(-2) current density with a Tafel slope of 42.9 mV dec(-1) in alkaline media. After the surface self-reconstruction induced by fluoride leaching under OER conditions, the surface of NiFe-OH-F was converted into highly mesoporous and amorphous NiFe oxide hierarchical structure, and the OER activity at eta = 220 mV increases over 58-fold. The corresponding eta at 10 mA cm(-2) decreases to 176 mV with an extreme low Tafel slope of 22.6 mV dec(-1); this performance is superior to that of the state-of-the-art OER electrocatalysts.

析氧反应（OER）是水分解系统、燃料电池和金属 - 空气电池中的关键过程，但通过简单方法开发高活性且稳定的OER催化剂是一项巨大挑战。在此，我们报道了一种原位动态表面自重构方法，它可以显著提高电催化剂的催化活性。通过一步水热法在泡沫镍上生长了一种含氟（F⁻）的氢氧化镍铁（NiFe - OH - F）纳米片阵列，在碱性介质中，该阵列需要243 mV的过电位（η）才能达到10 mA cm⁻²的电流密度，塔菲尔斜率为42.9 mV dec⁻¹。在析氧反应条件下，由氟化物浸出诱导表面自重构后，NiFe - OH - F的表面转化为高度介孔且无定形的镍铁氧化物分级结构，在η = 220 mV时，析氧反应活性提高了58倍以上。在10 mA cm⁻²时相应的η降低至176 mV，塔菲尔斜率极低，为22.6 mV dec⁻¹；这种性能优于最先进的析氧反应电催化剂。