It is of great significance to design a simple, robust, rapid, and sensitive method for detecting chemical oxygen demand (COD) in wastewater. A photoelectrochemical COD sensor based on linear photocurrent-concentration analytical principle has attracted tremendous attention in the on-site determination of COD. However, insufficient accuracy, linear range, and short lifetime have been the major challenges impeding the commercialization of this analytical method for COD testing. To overcome these challenges, a high-performance anatase-branch@hydrogenated rutile-nanorod TiO₂ (AB@H-RTNR) photoelectrode is fabricated. The as-prepared photoanodes successfully achieved sensitive determination of COD with a detection limit of 0.2 ppm (S/N = 3), an RSD% of 1.5 %, a wide linear detection range of 1.25−576 ppm and an average recovery rate fluctuating between 100 % ± 4 % for artificial wastewater sample analyses. Such performances are outstanding in comparison with the standard COD method. Furthermore, the AB@H-RTNR photoelectrode has a long lifetime, e.g., each electrode is capable of ca. 3000 measurements. The favorable performance of AB@H-RTNR can be attributed to the adoption of the in-situ growth method of TiO₂ nanostructure and the oxygen vacancies in crystal lattice generated by the hydrogenation process. The result suggests that the as-prepared AB@H-RTNR has overcome the barriers for practical application and final commercialization of this photocurrent-based PeCOD technology.

设计一种简单，耐用，快速而灵敏的检测废水中化学需氧量（COD）的方法具有重要意义。基于线性光电流浓度分析原理的光电化学化学需氧量传感器在化学需氧量的现场测定中引起了极大的关注。但是，精度不足，线性范围和寿命短已成为阻碍该分析方法用于COD测试的商业化的主要挑战。为了克服这些挑战，高性能的锐钛矿-分支@氢化金红石-纳米级TiO ₂制造了（AB @ H-RTNR）光电极。所制备的光阳极成功实现了COD的灵敏测定，检出限为0.2 ppm（S / N = 3），RSD％为1.5％，线性检测范围为1.25-576 ppm，平均回收率在100％±4％用于人造废水样品分析。与标准的COD方法相比，这种性能非常出色。此外，AB @ H-RTNR光电极的寿命很长，例如，每个电极大约可以 3000次测量。AB @ H-RTNR的良好性能归因于采用TiO ₂原位生长方法氢化过程产生的纳米结构和晶格中的氧空位。结果表明，所制备的AB @ H-RTNR克服了该基于光电流的PeCOD技术的实际应用和最终商业化的障碍。