Electric Field Effects on Photoelectrochemical Water Splitting: Perspectives and Outlook

Abstract

The grand challenges in renewable energy lie in our ability to comprehend efficient energy conversion systems, together with dealing with the problem of intermittency via scalable energy storage systems. Relatively little progress has been made on this at grid scale and two overriding challenges still need to be addressed: (i) limiting damage to the environment and (ii) the question of environmentally friendly energy conversion. The present review focuses on a novel route for producing hydrogen, the ultimate clean fuel, from the Sun, and renewable energy source. Hydrogen can be produced by light-driven photoelectrochemical (PEC) water splitting, but it is very inefficient; rather, we focus here on how electric fields can be applied to metal oxide/water systems in tailoring the interplay with their intrinsic electric fields, and in how this can alter and boost PEC activity, drawing both on experiment and non-equilibrium molecular simulation.

Hydrogen evolution with hot electrons on a plasmonic-molecular catalyst hybrid system

“…One possibility is the near-field enhancements caused by the local electric fields formed upon Au LSPR excitation. At the most basic level, near-fields can enhance charge separation and alignment of molecular dipoles 53 . However, such localised electric fields impact the hot carriers but cannot catalyse the reaction autonomously.…”

Plasmon-Driven Reaction Selectivity Tuning for Photoelectrochemical H2O2 Production

“…Since the selectivity of the PEC WOR is significantly affected by the tailored energy band structure and band-bending behavior, applying an electric field to the photoanode can be useful in manipulating the PEC reaction pathway and promoting H 2 O 2 production. − For this, the introduction of plasmonic nanostructures can be a promising strategy to apply near-field into the metal oxide photoanode via a localized surface plasmon resonance effect, which can accommodate and confine incident electromagnetic waves and thus localize the electric field near the surface of the structure by forming a strong near-field. − When the localized electric field resonantly interacts with the neighboring plasmonic nanostructures, the overlapping area can exhibit an even more intense electric field induced by a near-field coupling effect, such as gap plasmonic resonance and multipolar plasmonic resonance, which can induce the modulation of the energy band structures of the metal oxide photoanode. ,− The range and effectiveness of the near-field depends on the plasmonic depth profile of the light-absorbing substrate in the vicinity of the metal structures. , Recently, most research motivated by the plasmonic effect introduced Au NPs on semiconductor photoanodes to enhance the PEC OER performance. ,− However, these works were mostly focused on enhancing the photocurrent parameters to achieve a highly efficient WOR rather than tuning the reaction pathways and manipulating the reaction selectivities to produce the higher value chemical, compared to O 2 , i.e. H 2 O 2 .…”