Search

Self-replication, an important concept abstracted from reproduction, the key feature of life, remains vague in definition and lacking in clear interpretation in terms of its chemical mechanism. Mentioned frequently in discussions concerning the essence of life and its origin, the vague concept has caused a lot of uncertain statements, confusable references, and malposed debates, and has seriously held back efforts in this field. In this article, we try to improve the situation by a conceptual analysis in a more fundamental and clearer background. Self-replication in the substantial world could not mean anything but that 'an entity favors the production of its own.' The major chemical mechanism for such favoring is catalysis, which can be classified into speed- and direction-favoring types (the template-directing function is actually a type of direction-favoring catalysis). Molecular self-replication could be based on autocatalysis or self-metabolism; the self-replication of a complex entity could be based on autocatalytic and/or self-metabolic sets, and should involve a mechanism of self-division. This conceptual clarification sheds light on the dim areas concerning the essence of life and its origin. [ABSTRACT FROM AUTHOR]

The catalytic activity for methanol electro-oxidation on CoPc-Pt/C co-catalysts, prepared by impregnation method, was studied in details through electrochemical methods. Cyclic voltammetry (CV) result demonstrates that CoPc has higher forward anodic peak current density and jf / jb value (forward anodic peak current density/backward anodic peak current density) than Pt/C. Chronoamperometry (CA) analysis indicates that CoPc-Pt/C exhibits both excellent transient current density and stable current density for methanol electro-oxidation compared with Pt/C. Two main mechanisms related to the promotion of catalytic activity are as follows: CoPc-Pt/C has the activity of tolerance to carbonaceous intermediates, thus inhibiting the self-poisoning of catalysts; CoPc-Pt/C owns prominent intrinsic catalytic activity indicated by the apparent activation energy for methanol oxidation on CoPc-Pt/C, which is 18 kJ/mol, less than that on Pt and PtRu catalysts as reported. [ABSTRACT FROM AUTHOR]