Barnacle carapace-chitosan supported highly-efficient nano Al-W alloy electrocatalyst for sustainable bio-glycerol valorization: Environmental impact and cost analyses

Abstract

For the first time, highly efficient, corrosion resistant, and chemically stable rock barnacle carapace-derived chitosan (CH) supported non-noble nano aluminum-tungsten bimetallic-alloy based bifunctional electrocatalyst has been developed for waste pork lard-derived glycerol (WPLG) electrolysis in NaOH medium, ascertaining sustainability. An indirect bio-glycerol oxidation mechanism has been well executed to produce industrially important glyceric acid (6.65 mmol cm−2 h−1, 79.92% selectivity, ∼90% FE%) and formic acid (1.67 mmol cm−2 h−1, 18.07% selectivity) at the anode at ambient temperature and pressure. However, among the various prepared unsupported and supported nanocomposite electrocatalysts, the optimal aluminum-tungsten alloy anchored over chitosan renovated carbon nanotube (Al:W = 1:2 mole/mole) electrode rendered the lowest onset potential (0.95 V vs. RHE) and highest peak current density (119.61 mA cm−2) for the WPLG electrooxidation at the anode, coupled with H2 generation (28.55 ml cm−2 h−1) in the cathode in a membrane free electrochemical-cell by replacing sluggish oxygen evolution reaction. Comparing the electricity consumption for H2 production from various prepared catalysts, the supported optimum catalyst consumed 9.3% less energy (only 2.9 kWh/m3 H2) and 67.91% less corrosion current density as compared to the unsupported Al/W electrocatalyst, exhibiting excellent stability and durability (>200 cycles) due to good alloy-support interaction. Finally, a comprehensive life cycle impact assessment and life cycle costing of the overall WPLG electrolysis demonstrated 12.29% lower global warming potential (GWP100) while saving 11.03% of the cost compared to commercial glycerol electrolysis, which could procreate an effective approach toward inexpensive catalyst fabrication and its subsequent application for sustainable glycerol electrolysis.