Single-atom catalysts offering intriguing activity and selectivity are subject of intense investigation. Understanding the nature of single-atom active site and its dynamics under working state are crucial to improving their catalytic performances. Here, we identify at atomic level a general evolution of single atom into a near-free state under electrocatalytic hydrogen evolution condition, via operando synchrotron X-ray absorption spectroscopy. We uncover that the single Pt atom tends to dynamically release from the nitrogen-carbon substrate, with the geometric structure less coordinated to support and electronic property closer to zero valence, during the reaction. Theoretical simulations support that the Pt sites with weakened Pt-support interaction and more 5d density are the real active centers. The single-atom Pt catalyst exhibits very high hydrogen evolution activity with only 19 mV overpotential in 0.5 M H 2 SO 4 and 46 mV in 1.0 M NaOH at 10 mA cm −2 , and long-term durability in wide-pH electrolytes.

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Energy-saving photodetectors are the key components in future photonic systems and particularly, self-powered photoelectrochemical-type photodetectors (PEC-PDs) which depart completely from the classical solid-state junction device, have lately intrigued intensive interest to meet next-generation power-independent and environment-sensitive photodetection. Herein, we construct, for the first time, solar-blind PEC PDs based on self-assembled AlGaN nanostructures on silicon. Importantly, with the proper surface platinum (Pt) decoration, a significant boost of photon responsivity by more than an order of magnitude was achieved in the newly built AlGaN:Pt nanoarchitectures, demonstrating strikingly high responsivity of 45 mA/W and record fast response/recovery time of 47/20 ms without external power source. Such high solar-blind photodetection originates from the unparalleled material quality, fast interfacial kinetics, as well as high carrier separation efficiency which suggests that embracement of defectfree wide-bandgap semiconductor nanostructures with appropriate surface decoration offers an unprecedented opportunity for designing future energy-efficient and large-scale optoelectronic systems on silicon platform.

Searching for power‐independent, compact, and highly environment‐sensitive photodetectors is a critical step towards the realization of next‐generation energy‐efficient and sustainable integrated optoelectronic systems. Particularly, the deep ultraviolet (UV) band, which has large photon energy, is extremely suitable for environment monitoring and invisible light communication application. Herein, the demonstration of self‐powered deep UV solar‐blind photodetectors in a photoelectrochemical (PEC) cell configuration is reported, adopting wide bandgap n‐type aluminum gallium nitride (AlGaN) nanowires as photoelectrode. After decorating nanowires with noble metal ruthenium (Ru), the constructed solar‐blind PEC photodetectors exhibited excellent responsivity of 48.8 mA W‐1, fast response speed (rise time of 83 ms and decay time of 19 ms) with large photocurrent density of 55 μA cm‐2 at 254 nm illumination. Such superior performance can be attributed to, firstly and foremost, the successful synthesis of highly uniform and defect‐free n‐type AlGaN nanowires which ensures efficient photogeneration via effective light‐harvesting, and secondly, the boosted carrier separation and collection efficiency through Ru decoration. This novel nanoarchitecture enables deep UV photodetection to work stably with low energy consumption, intriguingly, opening the possibility for the development of high‐performance PEC photodetectors based on group III‐nitride semiconductors covering the entire spectral range from infrared to deep UV.