Two active electrochromic materials, vacancy-doped tungsten oxide (WO(3-x)) nanocrystals and amorphous niobium oxide (NbOx) glass are arranged into a mesostructured architecture. In a strategy applicable across electrochemical applications, the critical dimensions and interfacial connections in the nanocomposite are designed to optimize pathways for electrochemical charging and discharging. The result is an unprecedented optical range for modulation of visible and near-infrared solar radiation with rapid switching kinetics that indicate the WO(3-x) nanocrystal framework effectively pumps charge out of the normally sluggish NbOx glass. The material is durable for at least 2000 electrochemical cycles.

Regulating the complex environment accounting for the stability, selectivity, and activity of catalytic metal nanoparticle interfaces represents a challenge to heterogeneous catalyst design. Here we demonstrate the intrinsic performance enhancement of a composite material composed of gold nanoparticles (AuNPs) embedded in a bottom-up synthesized graphene nanoribbon (GNR) matrix for the electrocatalytic reduction of CO. Electrochemical studies reveal that the structural and electronic properties of the GNR composite matrix increase the AuNP electrochemically active surface area (ECSA), lower the requisite CO reduction overpotential by hundreds of millivolts (catalytic onset > -0.2 V versus reversible hydrogen electrode (RHE)), increase the Faraday efficiency (>90%), markedly improve stability (catalytic performance sustained over >24 h), and increase the total catalytic output (>100-fold improvement over traditional amorphous carbon AuNP supports). The inherent structural and electronic tunability of bottom-up synthesized GNR-AuNP composites affords an unrivaled degree of control over the catalytic environment, providing a means for such profound effects as shifting the rate-determining step in the electrocatalytic reduction of CO to CO, and thereby altering the electrocatalytic mechanism at the nanoparticle surface.

We report here the first solid-state, NIR-selective electrochromic devices. Critical to device performance is the arrangement of nanocrystal-derived electrodes into heteromaterial frameworks, where hierarchically porous ITO nanocrystal active layers are infiltrated by an ion-conducting polymer electrolyte with mesoscale periodicity. Enhanced coloration efficiency and transport are realized over unarchitectured electrodes in devices, paving the way towards new smart windows technologies.