NiFe-layer double hydroxide (NiFe-LDH) has been widely explored for oxygen evolution reaction (OER), but only a few works have been done for hydrogen evolution reaction (HER). Herein, NiFe-LDH is activated for HER and overall water splitting by depositing Ni(OH)₂ nanoparticle to form NiFe-LDH/Ni(OH)₂ composite electrocatalyst using two-step electrodeposition method. The electrocatalytic performance of NiFe-LDH/Ni(OH)₂ in alkaline condition greatly improves as compared to that with single-phase NiFe-LDH or Ni(OH)₂. At a higher overpotential of − 0.3 V, NiFe-LDH/Ni(OH)₂ composite could reach a current density of 180 mA/cm² which increases 3-fold as compared to a single-phase NiFe-LDH (60 mA/ cm²). More importantly, NiFe-LDH/Ni(OH)₂ composite can act as a bifunctional electrocatalyst for overall water splitting. The cell voltages at current densities of 10 and 100 mA/cm² are 1.6 and 1.8 V_RHE, respectively during the water splitting process. The great improvement of electrocatalytic activities after the formation of composite catalysts is due to the synergetic effect between NiFe-LDH and Ni(OH)₂ to efficiently accelerate the water dissociation step and electron transfer through Ni(OH)₂ layer. This work provides simple and robust electrodeposition technique to prepare NiFe-LDH/Ni(OH)₂ composite for activating HER and overall water splitting.

广泛研究了NiFe层双氢氧化物（NiFe-LDH）用于氧释放反应（OER），但仅进行了很少的氢释放反应（HER）工作。在此，通过两步电沉积法，通过沉积Ni（OH）₂纳米颗粒以形成NiFe-LDH / Ni（OH）₂复合电催化剂，活化NiFe-LDH用于HER和总水分解。与单相NiFe-LDH或Ni（OH）₂相比，碱性条件下NiFe-LDH / Ni（OH）₂的电催化性能大大提高。在较高的-0.3 V的超电势下，NiFe-LDH / Ni（OH）₂复合材料可以达到180 mA / cm ²的电流密度与单相NiFe-LDH（60 mA / cm ²）相比，它增加了3倍。更重要的是，NiFe-LDH / Ni（OH）₂复合材料可作为双功能电催化剂用于整体水分解。在水分解过程中，电流密度为10和100 mA / cm ^2时的电池电压分别为1.6和1.8 V _RHE。复合催化剂形成后电催化活性的极大提高是由于NiFe-LDH与Ni（OH）₂之间的协同作用，从而有效地加速了水离解步骤和电子通过Ni（OH）₂层的传递。这项工作提供了简单而强大的电沉积技术来制备NiFe-LDH / Ni（OH）₂ 用于活化HER和总水分解的复合材料。