光/电催化氨合成是氮还原领域的前沿研究方向之一，该技术有望通过利用清洁能源与现成原材料实现可持续氨生产。电催化氮还原反应过程存在高电势与低收率等问题。制备选择性吸附氮气并有效降低氮还原的中间反应活化能垒的催化剂成为解决上述问题的关键。二维材料中固有的高比表面积有利于暴露表面活性位点，而表面改性可定向设计形貌及电子结构，因此在光/电催化氨合成应用中显示出潜在优势。本文主要研究了两类二维材料及其光（电）催化氮还原性能。

（1）我们以简单水热法制备的二维镍铁双金属氢氧化物（NiFe-LDH）为前驱体，硒化合成双金属镍铁硒化物。Ni_0.75Fe_0.25Se₂在0.1 M Li₂SO₄电解质溶液中表现出较好的电催化氮还原性能：在-0.1 V vs. RHE电位下，氨产率为5.64 μg h^-1 cm^-2_cat.；法拉第效率为12.3%。水合Li⁺在催化剂表面易脱附从而增大氮气的吸附概率，因此电极界面作用可优化催化氮还原性能。硒化物中Fe原子掺杂引起电子轨道能量不均，其电子结构的改变导致硒化物出现晶格畸变与NiFe协同作用，会使其表面暴露出更多吸附位点。此外，Ni_0.75Fe_0.25Se₂中Se原子的弱电子捕获能力可以加快p-d耦合电子的转移，提高反应速率与电子利用率。因此Ni_0.75Fe_0.25Se₂作体系催化剂有利于电催化氮还原反应正向发生。

（2）我们将BiVO₄纳米颗粒原位负载在二维钛化碳材料（MXene）基底表面，合成BiVO₄@MXene-x/y用于光电催化氮还原反应。BiVO₄@MXene-1/1在0.5 M K₂SO₄电解质溶液中的光电催化氨产率为27.25 μg h^-1 cm^-2_cat.，对应的法拉第效率为17.54%。水合K⁺与催化剂表面Bi原子位点相斥，从而抑制析氢活性。光生载流子通过BiVO₄与MXene间异质结构建的电子传输通道加速载流子转移，从而促进氮还原反应发生同时提升光电催化氮还原的性能。光电催化有望通过高效利用一次能源（太阳能）来推动清洁光能与电能协同催化氮还原反应进程。

Photo/electrocatalytic nitrogen reduction is one of the frontier researches on cheap, clean and sustainable ammonia production. A catalyst that preferentially adsorbs nitrogen and reduces the activation energy of the reduction reaction can increase the ammonia yield of the process. With a high specific surface area that increases the probability of nitrogen adsorption and a modified electronic structure that exposes active sites, the two-dimensional material can catalyze nitrogen reduction reactions. This paper mainly studies two types of two-dimensional materials and their photo (electric) catalytic nitrogen reduction performance.

（1）We use the two-dimensional nickel-iron double hydroxide (NiFe-LDH) prepared by the hydrothermal method to synthesize nickel-iron selenide by selenization. In 0.1 M Li₂SO₄ electrolyte, at -0.1 V vs. RHE, the ammonia yield and Faraday efficiency of Ni_0.75Fe_0.25Se₂ are 5.64 μg h^-1 cm^-2_cat. and 12.3%, respectively. The weak adsorption of hydrated Li⁺ with a larger radius on the electrode interface can enhance nitrogen adsorption. Doping causes uneven electron orbital energy, resulting in lattice distortion of selenide and exposing more adsorption sites on the surface. In addition, the weak electron trapping power of Se atoms accelerates the transfer of p-d coupling electrons and improves the reaction rate and electron utilization.

（2）We load BiVO₄ nanoparticles in situ on the surface of a 2D titanium carbide material (MXene) substrate to synthesize BiVO₄@MXene-x/y for the photo-electrocatalytic NRR. Under photoelectric conditions, the ammonia yield of BiVO₄@MXene-1/1 in 0.5 M K₂SO₄ electrolyte solution is 27.25 μg h^-1 cm^-2_cat. and Faraday efficiency is 17.54%. The hydrated K⁺ repels the Bi atom sites on the catalyst surface, thereby inhibiting the hydrogen evolution activity. The photogenerated carriers accelerate the carrier transfer through the electron transport channel built by the heterostructure between BiVO₄ and MXene, so improving the performance of the photo-electrocatalytic NRR. Photo-electric catalysis is expected to promote the process of catalyzing NRR through the efficient use of primary energy (solar energy).