Developing low-cost optical hydrogen sensors for applications in the fields related to hydrogen economy has attracted great attentions, but still remains challenging. Herein, a new type of optical indicator based on Pd-decorated PdO nanoparticle nanonetworks (Pd-PdO NNs) is reported. Pd-PdO NNs have the capability to indicate the presence of hydrogen in concentration range of 0.5% to 100 vol% H₂ in air background by a tunable color change. Detailed investigations show the reduction of PdO in H₂ is an autocatalytic reaction, and decorated Pd species act as catalysts to accelerate the rate-determining step, so the response time can be dramatically shortened by more than 400 times. The as-prepared H₂ indicator does not require expensive detectors, and the discoloration process can be observed conveniently by naked eyes or quantitively analyzed by cameras on smartphones. Moreover, this work highlights the used indicator can be recycled and reactivated repeatedly due to the interconvertibility between Pd and PdO, which opens a new strategy toward extending the sensor lifetime and reducing the cost. As such, Pd-PdO NNs hold the promise to be used as low-cost eye-readable H₂ indicators that provide basic sensing services for a broad application scenarios.

开发用于氢经济相关领域的低成本光学氢传感器已经引起了极大的关注，但仍然具有挑战性。本文报道了一种基于 Pd 装饰的 PdO 纳米粒子纳米网络 (Pd-PdO NNs) 的新型光学指示器。Pd-PdO NN 能够通过可调节的颜色变化来指示空气背景中浓度范围为 0.5% 至 100 vol% H _{2的氢的存在。}详细研究表明，H ₂中 PdO 的还原是一种自催化反应，修饰的 Pd 物质作为催化剂加速了决速步骤，因此响应时间可以显着缩短 400 倍以上。制备好的 H ₂指示器不需要昂贵的探测器，变色过程可以方便地用肉眼观察或通过智能手机上的摄像头进行定量分析。此外，这项工作强调了由于 Pd 和 PdO 之间的互转换性，使用过的指示剂可以重复回收和重新激活，这为延长传感器寿命和降低成本开辟了新的策略。因此，Pd-PdO NN 有望用作低成本的肉眼可读 H ₂指标，为广泛的应用场景提供基本的传感服务。