var dataBarValueContext = new DataBarValueContext
{
    MaximumValue = new NumericValue(1),
    MinimumValue = new NumericValue(-1)
};
// Create the rule and set the desired formatting
var rule = new DataBarRule(dataBarValueContext)
{
    UseGradientFill = false,
    Direction = DataBarDirection.Context,
    FillColor = ThemableColor.FromColor(Colors.Green),
    NegativeFillColor = ThemableColor.FromColor(Colors.Red),
    ShowBarsOnly = true,
    AxisPosition = DataBarAxisPosition.Automatic
};

var conditionalFormat = new ConditionalFormatting(rule);

worksheet.Cells[0, 0, 1, 0].AddConditionalFormatting(conditionalFormat);
worksheet.Cells[0, 0].SetValue(0.5);
worksheet.Cells[1, 0].SetValue(-0.5);

foreach (FloatingChartShape chart in wsPureCompTemplate.Charts)
{
    foreach (SeriesGroup seriesGroup in chart.Chart.SeriesGroups)
    {
        foreach (SeriesBase series in seriesGroup.Series)
        {
            LineSeries lineSeries = series as LineSeries;
            if (lineSeries != null && lineSeries.Marker != null && lineSeries.Marker.Fill == null)
            {
                lineSeries.Marker.Fill = new NoFill();
            }

            ScatterSeries scatterSeries = series as ScatterSeries;
            if (scatterSeries != null && scatterSeries.Marker != null && scatterSeries.Marker.Fill == null)
            {
                scatterSeries.Marker.Fill = new NoFill();
            }
        }
    }
}