Introduction

Method

Instrument details

Results and discussion

Conclusion

References

Abstract

Plasmonic Ni nanoparticles were incorporated into LaFeO3 photocathode (LFO-Ni) to excite the surface plasmon resonances (SPR) for enhanced light harvesting for enhancing the photoelectrochemical (PEC) hydrogen evolution reaction. The nanostructured LFO photocathode was prepared by spray pyrolysis method and Ni nanoparticles were incorporated on to the photocathode by spin coating technique. The LFO-Ni photocathode demonstrated strong optical absorption and higher current density where the untreated LFO film exhibited a maximum photocurrent of 0.036 mA/cm2 at 0.6 V vs RHE, and when incorporating 2.84 mmol Ni nanoparticles the photocurrent density reached a maximum of 0.066 mA/cm2 at 0.6 V vs RHE due to the SPR effect. This subsequently led to enhanced hydrogen production, where more than double (2.64 times) the amount of hydrogen was generated compared to the untreated LFO photocathode. Ni nanoparticles were modelled using Finite Difference Time Domain (FDTD) analysis and the results showed optimal particle size in the range of 70–۱۰۰ nm for Surface Plasmon Resonance (SPR) enhancement.

Introduction

With climate change and global warming ever becoming the focus of concern for millions of people globally, there is a critical need to develop scalable and sustainable energy source assets. One of the possible way this can be accomplished is by harnessing the solar energy reaching the earth’s surface, which supplies enough energy every hour to meet humanities need for a year [1]. However, the predominant renewable energy sources, solar energy and wind energy, are highly intermittent and hence there is a dire need for the development of sustainable energy storage systems. The conversion of incoming photons from the sun light into storable chemical fuel (hydrogen), also known as solar fuel, is a highly attractive clean and sustainable energy storage solution. The stored hydrogen can be converted to electricity as per the demand using fuel cells. Currently, the major processes being explored for hydrogen generation are steam reforming [2,3], coal gasification [4], biomass derivatives [5], thermochemical [6] and biological processes [7]. However, most of these processes are energy intensive and generates a large carbon footprint. Photoelectrochemical (PEC) water splitting is a potential pathway in realising environmental friendly hydrogen production as it only requires semiconductor electrodes, water and sunlight [8]. The semiconductor materials require favourable band alignments for water reduction/oxidation, optimal bandgaps and high stability under reaction conditions [9]. Cu2O [10,11], WSe2 [12], CdTe [13], CuGaSe2 [8], Si [14], GaP [15] and InP [16] are photocathode materials which already have applications in solar assisted water splitting for hydrogen generation. However, due to availability, cost, stability and synthesis procedures there are limitations to their use. LaFeO3 (LFO), a non-toxic p-type semiconductor material with a direct bandgap of 2.4 eV, high stability and ability to generate hydrogen spontaneously without the need of an external bias [17], is a promising photocathode material for solar to hydrogen conversion. However, due to its low absorption coefficient, the current density is low, thus yielding lower amounts of hydrogen. Therefore, improving the material’s light extracting ability is crucial for improving the hydrogen yield capability of LFO.