Multi-Layer Kesterite-Based Photocathodes for NH 3 Photosynthesis from N 2 Reduction Reaction

The necessity of new methods to substitute the Haber-Bosch process in the NH synthesis, generating fewer greenhouse gases, and dispensing less energy, drove the investigation of the photoelectrocatalytic approach in the N reduction reaction (N2RR). For that, this work presents the synthesis and characterization of the layered CZTSSe/CdS/TiO photocathode decorated with Pt nanoparticles for application in NH production using the photoelectrocatalysis technique. The CZTSSe/CdS/TiO -Pt characterization showed a well-designed and stable photocatalyst synthesized layer by layer with an important contribution of the Pt nanoparticles for the catalyst performance, improving the photocurrent density and the charge transfer. The N2RR in a two-compartment photochemical cell with 0.1 mol L Na SO and 0.05 mol L H SO in the cathodic and anodic chamber, respectively, using CZTSSe/CdS/TiO -Pt and under 1 sun of light incidence and applied potential of -0.4 V reached 0.22 mmol L cm NH , a value 28 folds higher than using the catalyst without Pt modification. The superiority of N2RR under the photoelectrocatalysis technique was demonstrated compared to photocatalytic and electrocatalytic techniques, together with the investigation of the supporting electrolyte influence in the cathodic compartment. Additionally, that is the first time a kesterite-based photocathode has been applied to NH photosynthesis, showing excellent photoconversion capability.