Laser-Direct-Written Cr-Doped RuO2 Heterojunction for Acidic Oxygen Evolution Reaction

This work presents a rapid synthesis method for self-supported catalytic electrodes using laser as the sole heat source. We fabricated Cr-doped RuO 2 supported on titanium plate via laser direct writing as an oxygen evolution reaction (OER) anode for water splitting, and identified the optimal catalytic electrode by systematically investigating chromium doping ratios and laser ablation cycles. The results demonstrate that the catalytic electrode prepared with five repeated laser scanning cycles (300 W mm −2 power density, 100 mm min −1 scanning speed) exhibits superior performance. Among all samples, the 0.7Cr–Ru/Ti-5 electrode with a Cr/Ru atomic ratio of 7:10 shows the highest electrocatalytic activity, achieving a low overpotential of 174 mV@10 mA·cm −2 in 0.5 M H 2 SO 4 solution. Remarkably, it maintains stable operation for 70 h without noticeable potential degradation, indicating exceptional catalytic durability. This study establishes a novel laser-energy-driven strategy for synthesizing high-performance water electrolysis anodes with tunable characteristics. Graphical A novel (Cr 2 O 3 -RuO 2 -Ru)/Ti oxygen evolution electrode was rapidly fabricated using an innovative fibre laser ablation technique, differing from conventional methods. The catalyst was synthesized by subjecting precursor-coated titanium substrates to multiple laser ablations in an N 2 atmosphere. The high-temperature conditions generated reductive species locally, partially reducing ruthenium compounds to metallic Ru. Kinetic constraints and limited solid-phase diffusion hindered complete reduction of ruthenium species. Meanwhile, polyvinylpyrrolidone (PVP), rich in oxygen functional groups, reacted with residual ruthenium compounds to form RuO 2 . Under laser irradiation, chromium ions reacted with PVP's oxygen functional groups, leading to Cr 2 O 3 formation. Consequently, Cr 2 O 3 /RuO 2 /Ru active units were created on the titanium substrate.