The formaldehyde oxidation reaction(FOR)on a Cu-based electrocatalyst enables hydrogen(H_(2))at the anode in OH−solution,facilitating a bipolar H_(2) production system at ultra-low electrolysis voltage.However,the spe...The formaldehyde oxidation reaction(FOR)on a Cu-based electrocatalyst enables hydrogen(H_(2))at the anode in OH−solution,facilitating a bipolar H_(2) production system at ultra-low electrolysis voltage.However,the specific impact of*OH adsorption on the Cu surface regarding the FOR has been rarely investigated.Herein,the strong*OH adsorption Cu(S-OH Cu)electrode,which exhibits high activity and excellent stability of FOR,is developed to investigate the specific impact of*OH adsorption on the Cu surface during the FOR process.Impressively,the increased*OH adsorption on the Cu electrode,typically regarded as a poisoning effect that diminishes inherent FOR activity by reducing the adsorption of intermediate reactants,is firstly revealed as an OH-induced favorable reconstruction effect that significantly improves FOR stability.Specifically,the dual functions of OH-induced favoring reconstruction include accelerating the phase transition of the Cu(0)/Cu(I)redox cycle to refresh the active site and optimizing surface reconstruction to preferentially generate Cu(220)with stronger adsorption energy for H_(2)C(OH)O*and lower C−H barrier energy during FOR.This work provides a promising strategy for designing stable Cu electrocatalysts for FOR to produce hydrogen with extremely low energy input.展开更多
Inorganic minerals in mudstone are composed of clay minerals,carbonate and detrital minerals.Detrital minerals(such as quartz and feldspar)are mainly original deposit.However,clay minerals(kaolinite,illite,and chlorit...Inorganic minerals in mudstone are composed of clay minerals,carbonate and detrital minerals.Detrital minerals(such as quartz and feldspar)are mainly original deposit.However,clay minerals(kaolinite,illite,and chlorite)and carbonate(calcite and dolomite)are mostly diagenetic minerals.Furthermore,conversion of the four kinds of clay minerals are common.The formation of clay minerals and carbonate is controlled by temperature,pressure,p H,Eh and type of cations during diagenesis.Therefore mineral assemblage can indicate the characteristics and change of diagenetic environment.In addition to inorganic minerals,there are also organic matter of different sources and chemical properties in mudstone.Traditionally,it is considered that evolution of organic matter is controlled by thermal effect.Now studies show that inorganic and organic matter can interact with each other and form clay-organic complexes.This suggest that attention should be paid to the influence of diagenetic mineral assemblage and diagenetic environment on the evolution of organic matter* Samples of mudstone from 1500-4500m of the Palaeogene in the Dongying Depression,China,were collected to investigate the changes of mudstone diagenetic environment.XRD,thin section and SEM were used to detect diagenetic minerals and assemblage characteristics.Results showed that content of detrital minerals,which are floating in mud matrix or preserved as silt laminae,is basically unchanged from shallow to deep strata.Clay minerals which are gathered as argillaceous matrix or preserved as argillaceous laminae have growth and decline relation to carbonate which mainly appear as micropoikilitic ferriferous calcite and ferriferous dolomite.All these characteristics indicate that detrital minerals are exogenetic,whereas carbonate is diagenetic minerals.Based on the SEM analysis of the clay minerals,it was found that smectite present honeycomb and reticulate structure,while illite present filiform and schistose structure and there are growth and decline relationship between them.Nevertheless,hexagonal tabular and stratified kaolinite has the highest content from 2400m to3300m.Rosette and stratified chlorite shows increase trend when the burial depth is deeper than 3300m.These characteristics indicated that clay minerals are diagenetic minerals and there are conversions among the four types.Therefore form shallow to deep,three diagenetic mineral assemblage zones can be divided based on the characteristics of carbonate and clay minerals in mudstone.Namely,smectite+illite/smectite zone in the depth of 2000-2500m;kaolinite+illite/smectite zone in the depth of 2500-3300m and illite+chlorite+carbonate zone below 3300m.Previous studies showed that kaolinite is stable under acidic conditions,while other clay minerals and carbonate are stable under alkaline conditions.Hence according to mineral assemblages feature,it was inferred that diagenetic environment of mudstonehasundergonethechangeof alkaline-acid-alkaline.For the organic matter with different chemical properties in mudstone,the hydrocarbon generation will be different in the acidic and alkaline diagenetic environment even if the conditions of temperature and pressure are the same.Therefore,for hydrocarbon generation we should not only focus on thermal effect,but also pay more attention to the differences of diagenetic environment which have great significance for the understanding of hydrocarbon generation,hydrocarbon expulsion and reservoir formation in mudstone.展开更多
基金the National Natural Science Foundation of China(No.22372104)the Shenzhen Science and Technology Program(Nos.ZDSYS20220527171401003 and KQTD20190929173914967)+1 种基金Guangdong College Students Science and Technology Innovation Cultivation Special Fund Project(No.pdjh2024a315)The authors also acknowledge the Instrumental Analysis Center of Shenzhen University(Xili Campus)for their assistance on TEM observation.
文摘The formaldehyde oxidation reaction(FOR)on a Cu-based electrocatalyst enables hydrogen(H_(2))at the anode in OH−solution,facilitating a bipolar H_(2) production system at ultra-low electrolysis voltage.However,the specific impact of*OH adsorption on the Cu surface regarding the FOR has been rarely investigated.Herein,the strong*OH adsorption Cu(S-OH Cu)electrode,which exhibits high activity and excellent stability of FOR,is developed to investigate the specific impact of*OH adsorption on the Cu surface during the FOR process.Impressively,the increased*OH adsorption on the Cu electrode,typically regarded as a poisoning effect that diminishes inherent FOR activity by reducing the adsorption of intermediate reactants,is firstly revealed as an OH-induced favorable reconstruction effect that significantly improves FOR stability.Specifically,the dual functions of OH-induced favoring reconstruction include accelerating the phase transition of the Cu(0)/Cu(I)redox cycle to refresh the active site and optimizing surface reconstruction to preferentially generate Cu(220)with stronger adsorption energy for H_(2)C(OH)O*and lower C−H barrier energy during FOR.This work provides a promising strategy for designing stable Cu electrocatalysts for FOR to produce hydrogen with extremely low energy input.
文摘Inorganic minerals in mudstone are composed of clay minerals,carbonate and detrital minerals.Detrital minerals(such as quartz and feldspar)are mainly original deposit.However,clay minerals(kaolinite,illite,and chlorite)and carbonate(calcite and dolomite)are mostly diagenetic minerals.Furthermore,conversion of the four kinds of clay minerals are common.The formation of clay minerals and carbonate is controlled by temperature,pressure,p H,Eh and type of cations during diagenesis.Therefore mineral assemblage can indicate the characteristics and change of diagenetic environment.In addition to inorganic minerals,there are also organic matter of different sources and chemical properties in mudstone.Traditionally,it is considered that evolution of organic matter is controlled by thermal effect.Now studies show that inorganic and organic matter can interact with each other and form clay-organic complexes.This suggest that attention should be paid to the influence of diagenetic mineral assemblage and diagenetic environment on the evolution of organic matter* Samples of mudstone from 1500-4500m of the Palaeogene in the Dongying Depression,China,were collected to investigate the changes of mudstone diagenetic environment.XRD,thin section and SEM were used to detect diagenetic minerals and assemblage characteristics.Results showed that content of detrital minerals,which are floating in mud matrix or preserved as silt laminae,is basically unchanged from shallow to deep strata.Clay minerals which are gathered as argillaceous matrix or preserved as argillaceous laminae have growth and decline relation to carbonate which mainly appear as micropoikilitic ferriferous calcite and ferriferous dolomite.All these characteristics indicate that detrital minerals are exogenetic,whereas carbonate is diagenetic minerals.Based on the SEM analysis of the clay minerals,it was found that smectite present honeycomb and reticulate structure,while illite present filiform and schistose structure and there are growth and decline relationship between them.Nevertheless,hexagonal tabular and stratified kaolinite has the highest content from 2400m to3300m.Rosette and stratified chlorite shows increase trend when the burial depth is deeper than 3300m.These characteristics indicated that clay minerals are diagenetic minerals and there are conversions among the four types.Therefore form shallow to deep,three diagenetic mineral assemblage zones can be divided based on the characteristics of carbonate and clay minerals in mudstone.Namely,smectite+illite/smectite zone in the depth of 2000-2500m;kaolinite+illite/smectite zone in the depth of 2500-3300m and illite+chlorite+carbonate zone below 3300m.Previous studies showed that kaolinite is stable under acidic conditions,while other clay minerals and carbonate are stable under alkaline conditions.Hence according to mineral assemblages feature,it was inferred that diagenetic environment of mudstonehasundergonethechangeof alkaline-acid-alkaline.For the organic matter with different chemical properties in mudstone,the hydrocarbon generation will be different in the acidic and alkaline diagenetic environment even if the conditions of temperature and pressure are the same.Therefore,for hydrocarbon generation we should not only focus on thermal effect,but also pay more attention to the differences of diagenetic environment which have great significance for the understanding of hydrocarbon generation,hydrocarbon expulsion and reservoir formation in mudstone.
