Core-Shell Structured MXene@Carbon Nanodots as Bifunctional Catalysts for Solar-Assisted Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing nonprecious bifunctional electrocatalysts is crucial for efficient and cost-effective overall water splitting.
• Existing catalysts often lack high activity and durability across a wide pH range.

Purpose of the Study:

• To design and synthesize novel core-shell MXene@carbon (MX@C) nanodot hybrids.
• To evaluate their bifunctional catalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).
• To demonstrate their application in solar-assisted overall water splitting cells.

Main Methods:

• Synthesis of N-doped carbon shells grown heteroepitaxially on MXene cores to form MX@C nanodot hybrids.
• Electrochemical characterization of HER and OER activity in various pH media.
• Incorporation of MX@C nanodots as cocatalysts onto Mo:BiVO4 photoanodes for photoelectrochemical water splitting.
• Fabrication and testing of solar-assisted overall water splitting cells.

Main Results:

• MX@C nanodots exhibited enhanced HER activity with low onset potential (134 mV) and Tafel slope (32 mV/dec) at pH 14.
• MX@C/Mo:BiVO4 photoanodes achieved 1.5 times higher photocurrent density compared to pristine Mo:BiVO4.
• Solar-assisted water splitting cells using MX@C cathode and MX@C/Mo:BiVO4 photoanode showed enhanced current density (1.23 mA/cm²) and durability (>8 h).

Conclusions:

• The core-shell MX@C nanodot hybrids demonstrate excellent bifunctional catalytic performance for overall water splitting.
• The strong chemical and electronic coupling at the heterointerface facilitates catalytic kinetics for both HER and OER.
• These findings pave the way for developing highly efficient and durable nonprecious electrocatalysts for sustainable energy applications.