Carbon dots (CDs) have wide application potentials in optoelectronic devices, biology, medicine, chemical sensors, and quantum techniques due to their excellent fluorescent properties. However, synthesis of CDs with controllable spectrum is challenging because of the diversity of the CD components and structures. In this report, machine learning (ML) algorithms were applied to help the synthesis of CDs with predictable photoluminescence (PL) under the excitation wavelengths of 365 and 532 nm. The combination of precursors was used as the variable. The PL peaks of the strongest intensity ( ${\lambda }_{\mathrm{s}}$) and the longest wavelength ( ${\lambda }_{\mathrm{l}}$) were used as target functions. Among six investigated ML models, the random forest (RF) model showed outstanding performance in the prediction of the PL peaks.

Although chalcogenide anodes possess higher potassium storage capacity than intercalated-based graphite, their drastic volume change and the irreversible electrochemical reactions still hinder the effective electron/ion transfer during the potassiation/depotassiation process. To solve the above problems, this article proposes the synthesis of a lamellar nanostructure where graphene nanosheets are embedded with SnSb₂Se₄ nanoparticles (SnSb₂Se₄/GNS). In the product, fine monodisperse SnSb₂Se₄ nanoparticles are coupled with graphene nanosheets to form a porous network framework, which can effectively mitigate the drastic volume changes during electrode reactions and guarantee efficient potassium-ion storage through the synergistic interactions among multiple elements. Various electrochemical analyses prove that SnSb₂Se₄ inherits the advantages of the binary Sb₂Se₃ and SnSe while avoiding their disadvantages, confirming the synergistic effect of the ternary–chalcogenide system. When tested for potassium storage, the obtained composite delivers a high specific capacity of 368.5 mAh g⁻¹ at 100 mA g⁻¹ and a stable cycle performance of 265.8 mAh g⁻¹ at 500 mA g⁻¹ over 500 cycles. Additionally, the potassium iron hexacyanoferrate cathode and the SnSb₂Se₄/GNS anode are paired to fabricate the potassium-ion full cell, which shows excellent cyclic stability. In conclusion, this strategy employs atomic doping and interface interaction, which provides new insights for the design of high-rate electrode materials.