RESUMO
Interface modulation of nickel phosphide (Ni2 P) to produce an optimal catalytic activation barrier has been considered a promising approach to enhance the hydrogen production activity via water splitting. Herein, heteronuclei-mediated in situ growth of hollow Ni2 P nanospheres on a surface defect-engineered titanium carbide (Ti3 C2 Tx ) MXene showing high electrochemical activity for the hydrogen evolution reaction (HER) is demonstrated. The heteronucleation drives intrinsic strain in hexagonal Ni2 P with an observable distortion at the Ni2 P@Ti3 C2 Tx MXene heterointerface, which leads to charge redistribution and improved charge transfer at the interface between the two components. The strain at the Ni2 P@Ti3 C2 Tx MXene heterointerface significantly boosts the electrochemical catalytic activities and stability toward HER in an acidic medium via a combination between experimental results and theoretical calculations. In a 0.5 m H2 SO4 electrolyte, the Ni2 P@Ti3 C2 Tx MXene hybrid shows excellent HER catalytic performance, requiring an overpotential of 123.6 mV to achieve 10 mA cm-2 with a Tafel slope of 39 mV dec-1 and impressive durability over 24 h operation. This approach presents a significant potential to rationally design advanced catalysts coupled with 2D materials and transition metal-based compounds for state-of-the-art high efficiency energy conversions.
RESUMO
The design of nonprecious bifunctional electrocatalysts with high activity and prolonged durability in a wide pH range is essential for the development of the highly efficient, cost-effective, and simplified overall water splitting systems. Here, we report core-shell structured MXene@carbon (MX@C) nanodot hybrids with high bifunctional activity, where N-doped carbon shells are grown in a heteroepitaxial manner strongly interacting with the MXene core. The resulting MX@C nanodot hybrids show enhanced catalytic activity for electrochemical hydrogen evolution reaction (HER) in various pH media from 0 to 14. At pH 14, MX@C achieves the low onset potential of 134 mV at 10 mA/cm2 and reduced Tafel slope of 32 mV/dec due to the facilitated charge transfer along the recombination reaction. For the oxygen evolution reaction (OER), MX@C nanodots are incorporated onto the surface of molybdenum-doped bismuth vanadate (Mo:BiVO4) as a cocatalyst of the photoanode, thereby achieving 1.5 times higher photocurrent density than pristine Mo:BiVO4 at 1.23 V (vs reversible hydrogen electrode) due to the enhanced light absorption and charge transfer efficiency. The superiority of this hybrid catalyst is demonstrated implementing the solar-assisted overall water splitting cells based on the MX@C cathode and MX@C/Mo:BiVO4 photoanode. These cells show the enhancement of current density from 0.78 to 1.23 mA/cm2 with long-term durability over 8 h. These results are attributed to the facile surface catalytic kinetics of the chemically and electronically coupled MX@C hybrid at the heterointerface for both OER and HER.
