A portable air purification (AP) system has been built using filters coated with TiO₂/g-C₃N₄ (CNT-n) as an S-scheme heterojunction photocatalyst (n (in CNT-n) as the g-C₃N₄:TiO₂ molar ratio of 0.02 to 1). The AP (CNT-0.02) is identified as the best performer with the highest mineralization rate for formaldehyde (FA) by efficiently harnessing the intrinsic redox capabilities of each n-type semiconductor through the formation of an internal electric field at their interface. The superiority of AP (CNT-0.02) is validated in terms of clean air delivery rate [CADR] of 13.3 L min⁻¹ and quantum yield [QY] of 2.74 × 10⁻³ molecules photon⁻¹ against 5 ppm FA in dry air under low UV-A LED (1 W) light irradiation conditions. Its remarkable stability (e.g., over 5 reuse cycles) even at high FA levels (e.g., at 100 ppm) may also come from the synergistic adsorption-photocatalysis of FA molecules through the S-scheme charge transfer pathway to efficiently preserve their reactive intermediates. The noticeable reduction in performance is also observed with increasing moisture levels (e.g., in terms of CADR (L min⁻¹): 7.47 (at 30% relative humidity) vs. 13.3 (in dry air)) to reflect the combined effects of multiple processes (e.g., competitive adsorption, surface blocking, and alteration in reaction pathways), as supported by an in situ DRIFTS analysis. Nonetheless, the high FA conversion efficiency of CNT-0.02 under such humid conditions (CO₂ yield: 99.2%) may reflect the potential of H₂O vapor as co-reactant in stabilizing CH₂O₂/HCOO⁻ intermediates generated over the catalytic surface. These findings should help deliver a new path to upscale the design and process efficiency of S-scheme photocatalyst for practical applications.

中文翻译：

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石墨氮化碳/二氧化钛复合材料的卓越矿化潜力及其在构建针对气态甲醛的便携式光催化空气净化系统中的应用


使用涂有 TiO₂/g-C₃N₄ （CNT-n） 作为 S 型异质结光催化剂（n （在 CNT-n） 作为 g-C₃N₄：TiO₂ 摩尔比为 0.02 比 1）的过滤器构建了便携式空气净化 （AP） 系统。AP （CNT-0.02） 通过在界面处形成内部电场来有效利用每个 n 型半导体的固有氧化还原能力，被确定为甲醛 （FA） 矿化率最高的最佳表现者。AP （CNT-0.02） 的优越性在 13.3 L ^min-1 的清洁空气输送率 [CADR] 和 2.74 × ^10-3 分子光子^-1 相对于 5 ppm FA 的量子产率 [QY] 方面得到了验证在低 UV-A LED （1 W） 光照射条件下。即使在高 FA 水平（例如，100 ppm）下，其显着的稳定性（例如，超过 5 次重复使用循环）也可能来自 FA 分子通过 S 型电荷转移途径的协同吸附-光催化，以有效保留其反应性中间体。随着水分含量的增加（例如，根据 CADR （L ^min-1）：7.47（在 30% 相对湿度下）与 13.3（在干燥空气中）），性能也明显降低，以反映多个过程的综合影响（例如，竞争性吸附、表面封闭和反应途径的改变），如原位 DRIFTS 分析所支持的那样。尽管如此，CNT-0 的 FA 转换效率很高。02 在这种潮湿条件下（CO₂ 产率：99.2%）可能反映了 H₂O 蒸气作为共反应物稳定催化表面产生的 CH₂O₂/HCOO⁻ 中间体的潜力。这些发现将有助于为提高 S 型光催化剂的设计和工艺效率提供一条新的途径，以用于实际应用。