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Reversible electrodeposition and dissolution of manganese oxide (MnO 2 ) represent an emerging electrochromic system. However, challenges such as "dead MnO 2 " formation, limited optical modulation across a narrow wavelength range, and difficulties in scaling up have significantly hindered the development of MnO 2 reversible electrodeposition-based electrochromic windows. In this work, we introduced Fe 2+ /Fe 3+ mediator ions into the electrolyte to suppress the Jahn-Teller effect, thereby preventing the formation of "dead MnO 2 " and achieving stable and reversible MnO 2 deposition/dissolution. Furthermore, by employing WO 3 as the counter electrode, we developed a complementary electrochromic device based on ion insertion and metal oxide deposition. This complementary system exhibits color neutrality in the colored state and high optical contrast across the entire visible spectrum, with an average optical modulation of 67.3%, excellent cycling stability (85.0% retention after 3000 cycles), and capability to switch uniformly over areas as large as 100 cm 2 .

Efficient electrocatalysts for the hydrogen evolution reaction (HER) are significant for the utilization of hydrogen as a fuel, particularly under alkaline conditions. However, the sluggish kinetics of HER remains a challenge. Here we demonstrate an efficient HER catalyst comprising Ru and AgCl nanoparticles anchored on Ag nanowires (Ru/AgCl@Ag), which delivers a low overpotential of 12 mV at 10 mA cm -2 and a Tafel slope of 38 mV decade -1 . A high mass activity of 214 mA mg -1 at an overpotential of 25 mV and a long-term durability in 1.0 M KOH are observed. In combination with computational simulations, we find that the high electronegativity of chlorine in AgCl and d-band electrons from Ru synergistically destabilize the water molecule and modulate H adsorption/desorption on the surface of Ru/AgCl@Ag, respectively. This work opens a promising avenue for the facile design and application of highly active and stable composite electrocatalysts toward water splitting.

Transition metal dichalcogenides (TMDs) are a category of promising two-dimensional (2D) materials for the optoelectronic devices, and their unique characteristics include tunable band gap, nondangling bonds as well as compatibility to large-scale fabrication, for instance, chemical vapor deposition (CVD). MoS 2 is one of the first TMDs that is well studied in the photodetection area widely. However, the low photoresponse restricts its applications in photodetectors unless the device is applied with ultrahigh source-drain voltage ( V DS ) and gate voltage ( V GS ). In this work, the photoresponse of a MoS 2 photodetector was improved by a chemical in situ doping method using gold chloride hydrate. The responsivity and specific detectivity were increased to 99.9 A/W and 9.4 × 10 12 Jones under low V DS (0.1 V) and V GS (0 V), which are 14.6 times and 4.8 times higher than those of a pristine photodetector, respectively. The photoresponse enhancement results from chlorine n-type doping in CVD MoS 2  which reduces the trapping of photoinduced electrons and promotes the photogating effect. This novel doping strategy leads to great applications of high-performance MoS 2 photodetectors potentially and opens a new avenue to enhance photoresponse for other 2D materials.