Tailoring the electrochemical properties of a magnesium phosphate/g-C3N4 (P, S-doped) hybrid as a next-generation electrode for energy

초록

To address the critical need for high-performance electrode materials for next-generation energy storage, magnesium phosphate (MgP4O11) hybrids integrated with phosphorus (P)-and sulfur (S)-doped graphitic carbon nitride (g-C3N4), designated as the MgP-CN series, were synthesized using a multistep chemical synthesis approach. Structural and morphological analyses confirmed the formation of a well-crystallized porous nano-/ microsheet architecture of MgP4O11, and the optimized MgP-CN-3 composite exhibited a high specific surface area (14.07 m2/g) and enhanced electrical conductivity. In a three-electrode system, the optimized MgP-CN-3 electrode delivered an outstanding specific capacitance (capacity) of 640.4 F/g (106.7 mAh/g) at 4.0 A/g and remarkable cycling stability, retaining 99.5% of its initial capacitance after 10,000 cycles. This enhanced electrochemical performance was attributed to the synergistic interaction between the P-doped g-C3N4 and the biocompatible magnesium phosphate, which facilitated rapid charge transport and provided abundant redoxactive sites. Based on these findings, an asymmetric solid-state supercapacitor (ASSS) was fabricated using MgP-CN-3 as the cathode and reduced graphene oxide (rGO) as the anode in a polyvinyl alcohol (PVA)-KOH gel electrolyte. The fabricated MgP-CN-3//rGO ASSS device exhibited a wide operational voltage window of +1.6 V, achieving a specific capacitance (capacity) of 54.2 F/g (24.1 mAh/g), an energy density of 19.3 Wh/kg, and a power density of 800 W/kg at 1.0 A/g, along with excellent durability, retaining 95.7% of its capacitance after 10,000 cycles. Furthermore, series-connected ASSS devices successfully powered light-emitting diodes (LEDs), demonstrating their practical applicability. These findings highlight the strong potential of heteroatom-doped carbon nitride/metal phosphate hybrids as durable and high-performance electrode materials for advanced energy storage systems, including biomedical electronic devices.

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