UV-Visible-Near-Infrared-Driven Photoelectrocatalytic Urea Oxidation and Photocatalytic Urea Fuel Cells Based on Ruddlensden–Popper-Type Perovskite Oxide La2NiO4

Abstract

Photocatalysis and photoelectrocatalysis, as green and low-cost pollutant treatment technologies, have been widely used to simultaneously degrade pollutants and produce clean energy to solve the problems of environmental pollution and energy crisis. However, the disadvantages of photocatalysts in a narrow absorption range and low utilization rate of solar energy still hinder the practical application. Here we fabricate two-dimensional porous Ruddlensden–Popper type nickel-based perovskite oxide La2NiO4 as a noble metal-free photoanode for photoelectrocatalytic urea oxidation under full spectrum sunlight irradiation. The transient photocurrent density under near infrared (NIR) light (λ > 800 nm) can reach 50 μA cm−2. Urea wastewater was used as the fuel to obtain low-energy hydrogen production, and round-the-clock hydrogen production was achieved with the optimal yield of 22.76 μmol cm−2 h−1. Moreover, a photocatalytic urea fuel cell (PUFC) was constructed with La2NiO4 as the photoanode. The power density under UV-vis-NIR was 0.575 μW cm−2. Surprisingly, the filling factor (FF) under NIR light was 0.477, which was much higher than those under UV-vis-NIR and visible light. The results demonstrated that PUFCs constructed from low-cost nickel-based perovskite oxides have potential applications for low-energy hydrogen production and efficient utilization of sunlight.

Urea catalytic oxidation for energy and environmental applications

“…[291][292][293] p-UOR and e-UOR have recently emerged as promising approaches for urea/urine wastewater remediation. [294][295][296] At 60 min, the amount of N 2 reached 806 mmol, with an FE of 77.9%, demonstrating that N 2 was the primary product of urine degradation (97.5%). Meanwhile, the urine degradation rate remained at 81% after 5 runs, evidencing its good stability.…”

“…291–293 p-UOR and e-UOR have recently emerged as promising approaches for urea/urine wastewater remediation. 294–296 Shen et al employed a photoelectrochemical cell system that Cl˙ and ˙HO facilitate the conversion of urea–nitrogen into N 2 while degrading organics into CO 2 . In this process, WO 3 and Pd/Au served as the anode and the cathode, respectively, and afforded high removal efficiencies of 99.37% for TN and 50.91% for TOC.…”