Plasmon-Enhanced Solar-Driven Hydrogen Evolution Using Transition Metal Nitride Metasurface Broadband Absorbers

Broadband perfect absorbers in the visible region have attracted considerable attention in many fields, especially in solar thermophotovoltaic and energy harvesting systems. However, developing light absorbers with high absorptivity, thermal stability, and a broad bandwidth remains a great challenge. Here, we theoretically and experimentally demonstrate that a titanium nitride metasurface absorber exhibits broadband absorption with an average absorption of more than 92 % over a wavelength range of 400 nm to 750 nm. The increase in absorption is attributed to the localized surface plasmon resonance (LSPR). We demonstrate the plasmon-enhanced visible-light-driven hydrogen production from water using a polymer photocatalyst integrated with a TiN metasurface absorber. A 300 % increase in the hydrogen evolution rate was observed due to the LSPR that enhances the rates of light absorption, carrier separation, and hot-carrier transfer in polymer photocatalyst. These results enable a new approach to preparing high-efficiency solar energy harvesting systems. The concept is extensible to other types of photocatalyst such as 2D materials. In the end, we will also discuss the outlook for refractory metasurface in applications of solar energy harvesting systems.