Identifying And Unveiling the Role of Multivalent Metal States for Bidirectional UOR and HER Over Ni, Mo‐Trithiocyanuric Based Coordination Polymer

Abstract

Urea oxidation reaction (UOR), an ideal alternative to oxygen evolution reaction (OER), has received increasing attention for realizing energy‐saving H2 production and relieving pollutant degradation. Normally, most studied Ni‐based UOR catalysts pre‐oxidate to NiOOH and then act as active sites. However, the unpredictable transformation of the catalyst's structure and its dissolution and leaching, may complicate the accuracy of mechanism studies and limit its further applications. Herein, a novel self‐supported bimetallic Mo‐Ni‐C3N3S3 coordination polymers (Mo‐NT@NF) with strong metal–ligand interactions and different H2O/urea adsorption energy are prepared, which realize a bidirectional UOR/hydrogen evolution reaction (HER) reaction pathway. A series of Mo‐NT@NF is prepared through a one‐step mild solvothermal method and their multivalent metal states and HER/UOR performance relationship is evaluated. Combining catalytic kinetics, in situ electrochemical spectroscopic characterization, and density‐functional theory (DFT) calculations, a bidirectional catalytic pathway is proposed by N, S‐anchored Mo5+ and reconstruction‐free Ni3+ sites for catalytic active center of HER and UOR, respectively. The effective anchoring of the metal sites and the fast transfer of the intermediate H* by N and S in the ligand C3N3S3H3 further contribute to the fast kinetic catalysis. Ultimately, the coupled HER||UOR system with Mo‐NT@NF as the electrodes can achieve energy‐efficient overall‐urea electrolysis for H2 production.

Barium-induced lattice expansion of Ni(OH)2: enhancing catalytic urea oxidation activity for energy-saving H2 production

“…Deprotonated CON 2 further undergoes intramolecular N–N coupling, resulting in N 2 production and release. 48,49 In addition, the different perspectives of the Ba–Ni(OH) 2 structure are shown in Fig. 5(b–d).…”

Engineering organic polymers as emerging sustainable materials for powerful electrocatalysts

“…The different coordination types ( e.g. , Fe–S 2 N 2 , 134 Fe–S 4 , 134 Mo–S 2 N 2 , 133 Co/Ni–Se 4 , 135 and Co–O 2 N 2 136 ) have also been reported to regulate their intrinsic HER activity. One source of electrical conductivity in MOFs stems from their π-conjugated frameworks, enabled through the M–N x coordination between metal nodes and conjugated organic ligands.…”

Multi-interface engineering of nickel-based electrocatalysts for alkaline hydrogen evolution reaction

“…Liu et al reported the multi-interface coil-like NiS-Ni 2 P/Ni electrocatalyst prepared on NF. The NiS/Ni and Ni 2 P/Ni interfaces were served as electrochemical active sites and exhibited superior HER catalytic activity with overpotentials of 115 and 53 mV at 10 mA cm -2 in neutral and alkaline electrolyte [88] .…”