A nitrogen-superdoped graphene with diamond-like interlayer bonds is obtained via the radical chemistry of fluorographene, affording a symmetric supercapacitor with an energy density of 200 W h L⁻¹ at a power of 2.6 kW L⁻¹ and 143 W h L⁻¹ at 52 kW L⁻¹.

Single-atom catalysts (SACs) have demonstrated superior catalytic activity and selectivity compared to nanoparticle catalysts due to their high reactivity and atom efficiency. However, stabilizing SACs within hosting substrates and their controllable loading preventing single atom clustering remain the key challenges in this field. Moreover, the direct comparison of (co-) catalytic effect of single atoms vs nanoparticles is still highly challenging. Here, we present a novel ultrasound-driven strategy for stabilizing Pt single-atomic sites over highly ordered TiO₂ nanotubes. This controllable low-temperature defect engineering enables entrapment of platinum single atoms and controlling their content through the reaction time of consequent chemical impregnation. The novel methodology enables achieving nearly 50 times higher normalized hydrogen evolution compared to pristine titania nanotubes. Moreover, the developed procedure allows the decoration of titania also with ultrasmall nanoparticles through a longer impregnation time of the substrate in a very dilute hexachloroplatinic acid solution. The comparison shows a 10 times higher normalized hydrogen production of platinum single atoms compared to nanoparticles. The mechanistic study shows that the novel approach creates homogeneously distributed defects, such as oxygen vacancies and Ti³⁺ species, which effectively trap and stabilize Pt²⁺ and Pt⁴⁺ single atoms. The optimized platinum single-atom photocatalyst shows excellent performance of photocatalytic water splitting and hydrogen evolution under one sun solar-simulated light, with TOF values being one order of magnitude higher compared to those of traditional thermal reduction-based methods. The single-atom engineering based on the creation of ultrasound-triggered chemical traps provides a pathway for controllable assembling stable and highly active single-atomic site catalysts on metal oxide support layers.

Heavy metal pollutants are of great concern to environmental monitoring due to their potent toxicity. Electrochemical detection, one of the main techniques, is hindered by the mutual interferences of various heavy metal ions in practical use. In particular, the sensitivity of carbon electrodes to Cd²⁺ ions (one of the most toxic heavy metals) is often overshadowed by some heavy metals (e.g. Pb²⁺ and Cu²⁺). To mitigate interference, metallic particles/films (e.g. Hg, Au, Bi, and Sn) typically need to be embedded in the carbon electrodes. However, these additional metallic materials may face issues of secondary pollution and unsustainability. In this study, a metal-free and sustainable nanomaterial, namely cysteamine covalently functionalized graphene (GSH), was found to lead to a 6-fold boost in the Cd²⁺ sensitivity of the screen-printed carbon electrode (SPCE), while the sensitivities to Pb²⁺ and Cu²⁺ were not influenced in simultaneous detection. The selective enhancement could be attributed to the grafted thiols on GSH sheets with good affinity to Cd²⁺ ions based on Pearson's hard and soft acid and base principle. More intriguingly, the GSH-modified SPCE (GSH-SPCE) featured high reusability with extended cycling times (23 times), surpassing the state-of-art SPCEs modified by non-covalently functionalized graphene derivatives. Last, the GSH-SPCE was validated in tap water.

Supercapacitors offer a promising alternative to batteries, especially due to their excellent power density and fast charging rate capability. However, the cycling stability and material synthesis reproducibility need to be significantly improved to enhance the reliability and durability of supercapacitors in practical applications. Graphene acid (GA) is a conductive graphene derivative dispersible in water that can be prepared on a large scale from fluorographene. Here, we report a synthesis protocol with high reproducibility for preparing GA. The charging/discharging rate stability and cycling stability of GA were tested in a two-electrode cell with a sulfuric acid electrolyte. The rate stability test revealed that GA could be repeatedly measured at current densities ranging from 1 to 20 A g⁻¹ without any capacitance loss. The cycling stability experiment showed that even after 60,000 cycles, the material kept 95.3% of its specific capacitance at a high current density of 3 A g⁻¹. The findings suggested that covalent graphene derivatives are lightweight electrode materials suitable for developing supercapacitors with extremely high durability.

The surface of a zinc metal anode was mapped using SECM. Slow Zn²⁺ transport can be caused by an insulating SEI (ZHS or ZnO) or horizontally plated zinc. Fast Zn²⁺ transport can be caused by a protruding morphology or a more conducting SEI.