The major findings in this report are (i) development of nanocomposite photocatalyst working through Z-scheme charge transfer pathway across the heterojunction, (ii) utilization of direct sunlight as the photo-source, and (iii) prospect of ligand-hole in photocatalysis through enhanced sub-band gap absorption. The photocatalysts, namely LaNiO₃, g-C₃N₄ and LaNiO₃/g-C₃N₄ nanocomposites were synthesized via facile route and were characterized for their structure, morphology, microstructure, texture, elemental mapping and surface oxidation states by using several physicochemical techniques. The photocatalytic performance of the nanocomposite was tested through the degradation of hazardous azo dye pollutants, namely reactive black 5 and methylene blue as well as the colorless antibiotic-pollutant tetracycline hydrochloride in aqueous solution in presence of natural sunlight with excellent recycling activity. The 10%LaNiO₃/g-C₃N₄ nanocomposite sample shows the best catalytic activity, degrading respectively 94%, 98.6% and 88.1% of reactive black 5, methylene blue and tetracycline hydrochloride in 60, 180 and 120 min. The photocatalytic activity of the nanocomposite phase is several times superior to that of the pure phases. The improvements of photocatalytic activity of g-C₃N₄ in the nanocomposite have been rationalized through the construction of direct Z-scheme heterojunction and suppression of electron–hole pair recombination efficiency. The enhanced photo-absorption of the nanocomposite can possibly be related to sub-bandgap absorption, which is associated to the midgap state originating from ligand-hole formation or defects in the structure. The photodegradation process is mediated through the formation of super oxide radical (^˙O₂^¯) and hole (h⁺) as the main responsible species.

本报告的主要发现是（i）通过跨异质结的 Z 型电荷转移途径工作的纳米复合光催化剂的开发，（ii）利用直射阳光作为光源，以及（iii）配体空穴在光催化中的前景通过增强的子带隙吸收。光催化剂，即LaNiO ₃、gC ₃ N ₄和LaNiO ₃ /gC ₃ N ₄纳米复合材料通过简便的途径合成，并通过使用多种物理化学技术对其结构、形态、微观结构、纹理、元素映射和表面氧化态进行了表征。该纳米复合材料的光催化性能通过在自然阳光下降解有害偶氮染料污染物，即活性黑 5 和亚甲蓝以及无色抗生素污染物盐酸四环素，在自然阳光下具有优异的回收活性。10%LaNiO ₃ /gC ₃ N ₄纳米复合样品表现出最好的催化活性，在 60、180 和 120 分钟内分别降解 94%、98.6% 和 88.1% 的活性黑 5、亚甲蓝和盐酸四环素。纳米复合相的光催化活性是纯相的数倍。_{gC 3} N ₄光催化活性的提高通过构建直接 Z 型异质结和抑制电子 - 空穴对复合效率，使纳米复合材料中的结构合理化。纳米复合材料增强的光吸收可能与亚带隙吸收有关，亚带隙吸收与源自配体空穴形成或结构缺陷的中带隙状态有关。光降解过程是通过形成超氧化物自由基 ( ^˙ O ₂ ^¯ ) 和空穴 (h ⁺ ) 作为主要负责物种来介导的。