2649598 eNRR electrochemical nitrogen reduction reaction 110 2649604 eNRR Electrochemical nitrogen reduction 4 2649603 eNRR electrocatalytic nitrogen reduction 3 2649602 eNRR Electrocatalytic reduction of nitrogen to ammonia 1 2649606 eNRR electrochemical reduction of nitrogen 1 2649605 eNRR electrolytes at ambient temperature and pressure 1