Perovskite materials have attracted much attention in heterogeneous catalysis. Here, we report a perovskite type material LaNiO_3-δ (LNO) for degradation of methyl orange (MO) azo dye in aqueous solutions under dark ambient conditions (room temperature, atmospheric pressure) without additional lights or chemical stimulants. The high degradation percentage of 5 ppm MO with 1.5 g/L LNO was 94.3% after 4 h with a stirring speed of 500 rpm. Reactions under nitrogen, oxygen and carbon dioxide conditions were performed with efficiencies of 19.6%, 7.1%, and 96.8% respectively after 6 h to understand the mechanism. MO was shown to degrade under dark ambient condition via main intermediates, sulfanilic acid anion and N,N-dimethyl-p-phenylenediamine (DPD), by electrospray ionization mass spectrometry (ESI/MS) and high performance liquid chromatography (HPLC). Degradation of MO under such a mild condition is due to two synergic effects proposed by means of XRD, FTIR, TGA, SEM, and XPS. Nickel is oxidized during MO degradation; lanthanum carbonate (La-analog calkinsite) is formed on the LNO surface due to the aqueous solution environment and speeds up azo bond cleavage. This work unravels the mechanism behind MO degradation by LNO under dark ambient conditions for the first time. It is a fundamental information on perovskite for dye degradation, especially for lanthanum series of perovskite. Excellent perovskite materials should be tailorable for water remediation applications considering the large variety of perovskites in terms of constituents and composition.

钙钛矿材料在非均相催化中引起了广泛的关注。在这里，我们报道了一种钙钛矿型材料LaNiO3 _-δ（LNO），用于在黑暗环境条件（室温，大气压）下在无其他光或化学刺激剂的情况下降解水溶液中的甲基橙（MO）偶氮染料。4 h后，以500 rpm的搅拌速度，含1.5 g / L LNO的5 ppm MO的高降解百分比为94.3％。6小时后，在氮气，氧气和二氧化碳条件下进行的反应效率分别为19.6％，7.1％和96.8％，以了解机理。在黑暗的环境条件下，MO可通过主要中间体磺胺酸阴离子和N，N-二甲基-p降解-苯二胺（DPD），通过电喷雾电离质谱（ESI / MS）和高效液相色谱（HPLC）。在这种温和条件下，MO的降解归因于通过XRD，FTIR，TGA，SEM和XPS提出的两种协同作用。镍在MO降解过程中被氧化；由于水溶液环境的缘故，LNO表面形成了碳酸镧（La-analog calkinsite），并加速了偶氮键的裂解。这项工作首次揭示了在黑暗环境条件下LNO导致MO降解的机理。它是钙钛矿用于染料降解的基本信息，尤其是镧系钙钛矿。考虑到钙钛矿的成分和组成种类繁多，优秀的钙钛矿材料应适合水修复应用。